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#pike __REAL_VERSION__ 
#require constant(___Mysql) 
 
//! This class provides some abstractions on top of an SQL table. 
//! 
//! At the core it is generic for any SQL database, but the current 
//! implementation is MySQL specific on some points, notably the 
//! semantics of AUTO_INCREMENT, the quoting method, knowledge about 
//! column types, and some conversion functions. Hence the location in 
//! the @[Mysql] module. 
//! 
//! Among other things, this class handles some convenient conversions 
//! between SQL and pike data types: 
//! 
//! @ul 
//! @item 
//!   Similar to @[Sql.big_typed_query], SQL integer and floating 
//!   point columns are converted to/from pike ints and floats, and 
//!   SQL NULLs are converted to/from the @[Val.null] object. 
//! 
//!   MySQL DECIMAL columns are converted to/from @[Gmp.mpq] objects 
//!   if they have one or more decimal places, otherwise they are 
//!   converted to/from ints. 
//! 
//! @item 
//!   MySQL TIMESTAMP columns are converted to/from pike ints 
//!   containing unix timestamps. This conversion is done on the MySQL 
//!   side using the UNIX_TIMESTAMP and FROM_UNIXTIME functions, which 
//!   means that the conversion is not susceptible to offsets due to 
//!   time zone differences etc. There is however one special case 
//!   here that MySQL doesn't handle cleanly - see note below. 
//! 
//! @item 
//!   Other SQL types are kept in string form. That includes DATE, 
//!   TIME, and DATETIME, which are returned as MySQL formats them. 
//! 
//!   Note that @[Sql.mysql] can handle conversions to/from Unicode 
//!   strings for text data types. If that is enabled then this class 
//!   also supports that conversion. 
//! 
//! @item 
//!   There are debug checks (with the DEBUG define) that verify the 
//!   incoming pike types, to avoid bugs which could otherwise be 
//!   hidden by implicit casts on the SQL side. The date and time 
//!   types (except TIMESTAMP) can be sent either as strings or 
//!   integers (e.g. either "2010-01-01" or 20100101). 
//! @endul 
//! 
//! This class can also optionally simulate an arbitrary set of fields 
//! in each table row: If a field name is the same as a column then 
//! the column is accessed, otherwise it accesses an entry in a 
//! mapping stored in a special BLOB column which is usually called 
//! "properties". 
//! 
//! @note 
//! Although SQL is case insensitive on column names, this class 
//! isn't. 
//! 
//! @note 
//! The generated SQL queries always quote table and column names 
//! according to MySQL syntax using backticks (`). However, literal 
//! backticks in names are not quoted and might therefore lead to SQL 
//! syntax errors. This might change if it becomes a problem. 
//! 
//! @note 
//! The handling of TIMESTAMP columns in MySQL (as of 5.1 at least) 
//! through UNIX_TIMESTAMP and FROM_UNIXTIME has one problem if the 
//! active time zone uses daylight-saving time: 
//! 
//! Apparently FROM_UNIXTIME internally formats the integer to a MySQL 
//! date/time string, which is then parsed again to set the unix 
//! timestamp in the TIMESTAMP column. The formatting and the parsing 
//! uses the same time zone, so the conversions generally cancel 
//! themselves out. However, there is one exception with the 1 hour 
//! overlap in the fall when going from summer time to normal time. 
//! 
//! E.g. if the active time zone on the connection is Central European 
//! Time, which uses DST, then setting 1130630400 (Sun 30 Oct 2005 
//! 2:00:00 CEST) through "INSERT INTO foo SET ts = 
//! FROM_UNIXTIME(1130630400)" actually sets the ts column to 
//! 1130634000 (Sun 30 Oct 2005 2:00:00 CET). 
//! 
//! The only way around that problem is apparently to ensure that the 
//! time zone used on the connection is one which doesn't use DST. 
//! E.g. UTC is a reasonable choice, which can be set on the 
//! connection through "SET time_zone = '+00:00'". That is not done 
//! automatically by this class. 
 
#ifdef SQLTOOLS_UPDATE_DEBUG 
#define UPDATE_MSG(X...) werror (X) 
#else 
#define UPDATE_MSG(X...) 0 
#endif 
 
// Ideas for the future: 
// o  Generalize to support different db backends. 
// o  Add hooks to make it possible to cache the record mappings. 
// o  Make it possible to replace the encode/decode functions for the 
//    properties column. 
// o  Make it possible to specify custom conversion functions for 
//    individual fields. 
// o  Add optional caching of compiled queries. 
 
function(void:Sql.Sql) get_db; 
//! Callback to get a database connection. 
 
string table; 
//! The table to query or change. Do not change. 
 
string id_col; 
//! The column containing the AUTO_INCREMENT values (if any). 
 
array(string) pk_cols; 
//! The column(s) containing the primary key, in order. Typically it 
//! is the same as @expr{({@[id_col]})@}. 
 
string prop_col; 
//! The column containing miscellaneous properties. May be zero if 
//! this feature is disabled. Do not change. 
 
int prop_col_max_length; 
//! Maximum length of the value @[prop_col] can hold. Only applicable 
//! if @[prop_col] is set. Do not change. 
 
mapping(string:string) col_types; 
//! Maps the names of the table columns to the types @[SqlTable] will 
//! handle them as. This is queried from the database in @[create]. Do 
//! not change. 
 
protected mapping(string:int(1..1)) timestamp_cols; 
// Mapping tracking all TIMESTAMP columns. 
 
protected mapping(string:int(1..1)) datetime_cols; 
// Mapping tracking all date and time columns (except TIMESTAMP), 
// which can be sent either as strings or integers. 
 
protected string query_charset; 
// Mysql charset to use in queries. This is dictated by the table and 
// column names. If none of them are wide, we always use latin1 to 
// avoid the encoding overhead in Sql.mysql (even though that is not 
// strictly correct - mysql latin1 have some different chars in the 
// high control char range of iso-8859-1, but we ignore that). If wide 
// identifiers are found, this is zero to let Sql.mysql fix the 
// charsets, and it better be in unicode encode mode then. This does 
// not affect string constants since we always specify the charset for 
// every string literal. 
 
// Converts mysql types to pike types for col_types. All types not 
// mentioned here become "string". 
protected constant mysql_types_map = ([ 
  "float": "float", "double": "float", 
  "char": "int", "short": "int", 
  "int24": "int", "long": "int", "longlong": "int", 
  "timestamp": "int", "bit": "int", 
  "decimal": "float", "newdecimal": "float", 
]); 
 
// Mysql decimal types. These are represented as integers if they have 
// no fraction part, otherwise as Gmp.mpq objects. 
protected constant mysql_decimal_types = ([ 
  "decimal": 1, "newdecimal": 1, 
]); 
 
protected constant mysql_datetime_types = ([ 
  "datetime": 1, "date": 1, "time": 1, "year": 1, 
]); 
 
// Cache for _sizeof(). 
protected int num_entries = -1; 
 
protected void invalidate_cache() 
{ 
  num_entries = -1; 
} 
 
// FIXME: Add a setting to be able to "deprecate" columns for 
// migration from a column to a field in the properties blob. The 
// deprecation means the column will be queried, but the value will be 
// put into the properties mapping on update. 
 
// FIXME: Conversely, add a setting to deprecate properties be able to 
// migrate them to columns. Normally it solves itself since properties 
// have priority over columns, but select() and get() need to be aware 
// of such columns so they don't incorrectly skip prop_col altogether 
// in the query. 
 
protected void create (function(void:Sql.Sql) get_db, 
                       string table, 
                       void|string prop_col) 
//! Creates an @[SqlTable] object for accessing (primarily) a specific 
//! table. 
//! 
//! @param get_db 
//! A function that will be called to get a connection to the database 
//! containing the table. 
//! 
//! @param table 
//! The name of the table. 
//! 
//! @param prop_col 
//! The column in which all fields which don't have explicit columns 
//! are stored. It has to be a non-null blob or varbinary column. If 
//! this isn't specified and there is such a column called 
//! "properties" then it is used for this purpose. Set to @expr{"-"@} 
//! to force this feature to be disabled. 
{ 
  this::get_db = get_db; 
  this::table = table; 
 
  Sql.Sql conn = get_db(); 
 
  query_charset = String.width (table) == 8 && "latin1"; 
 
  { 
    col_types = ([]); 
    timestamp_cols = ([]); 
    datetime_cols = ([]); 
    array(mapping(string:mixed)) col_list = 
      conn->list_fields (string_to_utf8 (table)); 
    mapping(string:mixed) prop_col_info; 
 
    foreach (col_list, mapping(string:mixed) col_info) { 
      string name = utf8_to_string (col_info->name); 
      if (String.width (name) > 8) query_charset = 0; 
      if (col_types[name]) 
        error ("Strange duplicate column %O in %O\n", name, col_list); 
      if (mysql_decimal_types[col_info->type] && !col_info->decimals) 
        col_types[name] = "int"; 
      else 
        col_types[name] = mysql_types_map[col_info->type] || "string"; 
      if (col_info->type == "timestamp") timestamp_cols[name] = 1; 
      if (mysql_datetime_types[col_info->type]) datetime_cols[name] = 1; 
      if (name == (prop_col || "properties")) 
        prop_col_info = col_info; 
    } 
 
    if (prop_col != "-") { 
      if (prop_col_info) 
        if (!prop_col_info->flags->binary || 
            !prop_col_info->flags->not_null || 
            !(<"var string", "blob">)[prop_col_info->type]) 
          prop_col_info = 0; 
      if (prop_col && !prop_col_info) 
        error ("Table doesn't have a non-null binary column %O " 
               "to store extra fields in.\n", prop_col); 
      if (prop_col_info) { 
        if (!prop_col_info->length) 
          error ("Unable to determine maximum length of the property " 
                 "column %O. Got column info: %O\n", prop_col, prop_col_info); 
        this::prop_col = prop_col_info->name; 
        this::prop_col_max_length = prop_col_info->length; 
      } 
    } 
  } 
 
  foreach (conn->query ("SHOW COLUMNS FROM `" + table + "`"), 
           mapping(string:string) col_info) 
    if (col_info->Extra == "auto_increment") { 
      id_col = col_info->Field; 
      break; 
    } 
 
  { 
    mapping(int:string) pkc = ([]); 
    foreach (conn->query ("SHOW INDEX FROM `" + table + "`"), 
             mapping(string:string) ind_col) 
      if (ind_col->Key_name == "PRIMARY") 
        pkc[(int) ind_col->Seq_in_index] = ind_col->Column_name; 
    pk_cols = values (pkc); 
    sort (indices (pkc), pk_cols); 
  } 
} 
 
protected string _sprintf (int flag) 
{ 
  return flag == 'O' && 
    sprintf ("%s(%O)", 
             function_name (object_program (this)) || "SqlTable", 
             table); 
} 
 
local string quote (string s) 
//! Quotes a string literal for inclusion in an SQL statement, e.g. in 
//! a WHERE clause to @[select]. 
//! 
//! @note 
//! Most functions here take raw string literals. Quoting is seldom 
//! necessary. 
{ 
  // Hardwired mysql quoting since we don't support anything else 
  // (yet). The original ought to be in a module.. :P 
  return predef::replace(s, 
                         ({ "\\", "\"", "\0", "\'", "\n", "\r" }), 
                         ({ "\\\\", "\\\"", "\\0", "\\\'", "\\n", "\\r" })); 
} 
 
protected int argspec_counter; 
 
local string handle_argspec (array argspec, mapping(string:mixed) bindings) 
//! Helper function for use with array style arguments. 
//! 
//! Many functions in this class can take WHERE expressions etc either 
//! as plain strings or as arrays. In array form, they work like when 
//! @[Sql.Sql.query] is called with more than one argument: 
//! 
//! The first element in the array is a string containing the SQL 
//! snippet. If the second element is a mapping, it's taken as a 
//! bindings mapping, otherwise the remaining elements are formatted 
//! using the first in @expr{sprintf@} fashion. See @[Sql.Sql.query] 
//! for further details. 
//! 
//! This function reduces an argument on array form to a simple 
//! string, combined with bindings. @[bindings] is a mapping that is 
//! modified to contain the new bindings. 
//! 
//! @note 
//! The @[quote] function can be used to quote string literals in the 
//! query, to avoid the array format. 
//! 
//! @returns 
//! Return the SQL snippet in string form, possibly with variable 
//! bindings referring to @[bindings]. 
{ 
  if (sizeof (argspec) == 2 && mappingp (argspec[1])) { 
    foreach (argspec[1]; string|int var; mixed val) 
      bindings[var] = val; 
    return argspec[0]; 
  } 
  else 
    return Sql.sql_util.handle_extraargs (argspec[0], argspec[1..], 
                                          bindings)[0]; 
} 
 
// Implicit connection handling. 
 
int insert (mapping(string:mixed)... records) 
//! Inserts one or more records into the table using an INSERT 
//! command. An SQL error is thrown if a record conflicts with an 
//! existing one. 
//! 
//! A record is represented as a mapping with one entry for each 
//! column or property (if @[prop_col] is used). The values must be of 
//! the right type for the column: Integers for integer columns, 
//! floats for floating point columns, strings for all other data 
//! types, and @[Val.null] for the SQL NULL value. 
//! 
//! If the property feature is used (i.e. if @[prop_col] is set) then 
//! any entries in the record mapping that don't match a column are 
//! treated as properties and are stored encoded in the @[prop_col] 
//! column. Note that column names are matched with case sensitivity. 
//! Properties may store any pike data type (as long as it is accepted 
//! by @[encode_value_canonic]). 
//! 
//! If @[id_col] is set and that column doesn't exist in a record 
//! mapping then the field is added to the mapping with the value that 
//! the record got. This currently only works for the first record 
//! mapping if there are several. 
//! 
//! @returns 
//! The value of the @[id_col] column for the new record. If several 
//! records are inserted at once then the value for the first one is 
//! returned. Zero is returned if there is no @[id_col] column. 
//! 
//! @seealso 
//! @[insert_ignore], @[replace], @[insert_or_update] 
{ 
  return conn_insert (get_db(), @records); 
} 
 
int insert_ignore (mapping(string:mixed)... records) 
//! Inserts one or more records into the table using an INSERT IGNORE 
//! command. If some of the given records conflict with existing 
//! records then they are ignored. 
//! 
//! Zero is returned if all records were ignored. The record mapping 
//! is updated with the @[id_col] record id only if a single record is 
//! given. Otherwise this function behaves like @[insert]. 
//! 
//! @seealso 
//! @[insert], @[replace] 
{ 
  return conn_insert_ignore (get_db(), @records); 
} 
 
int replace (mapping(string:mixed)... records) 
//! Inserts one or more records into the table using a REPLACE 
//! command. If some of the given records conflict with existing 
//! records then they are replaced. 
//! 
//! Otherwise this function behaves like @[insert]. 
//! 
//! @seealso 
//! @[insert], @[insert_ignore] 
{ 
  return conn_replace (get_db(), @records); 
} 
 
void update (mapping(string:mixed) record, 
             void|int(0..2) clear_other_fields) 
//! Updates an existing record. This requires a primary key and that 
//! @[record] contains values for all primary key columns. If 
//! @[record] doesn't correspond to any existing record then nothing 
//! happens. 
//! 
//! Updating a record normally means that all fields in @[record] 
//! override those stored in the table row, while all other fields 
//! keep their values. 
//! 
//! It's the same for properties (i.e. fields that don't correspond to 
//! columns) which are stored in the @[prop_col] column. If that 
//! column needs to be updated then by default the old value is 
//! fetched first, which means the update isn't atomic in that case. A 
//! property can be removed altogether by giving it the value 
//! @[Val.null] in @[record]. 
//! 
//! If @[clear_other_fields] is 1 then all old properties are replaced 
//! by the new ones instead of merged with them, which avoids the 
//! extra fetch. If @[clear_other_fields] is 2 then additionally all 
//! unmentioned columns are reset to their default values. 
//! 
//! For more details about the @[record] mapping, see @[insert]. 
//! 
//! @seealso 
//! @[insert_or_update] 
{ 
  conn_update (get_db(), record, clear_other_fields); 
} 
 
int insert_or_update (mapping(string:mixed) record, 
                      void|int(0..2) clear_other_fields) 
//! Insert a record into the table using an INSERT ... ON DUPLICATE 
//! KEY UPDATE command: In case @[record] conflicts with an existing 
//! record then it is updated like the @[update] function would do, 
//! otherwise it is inserted like @[insert] would do. 
//! 
//! If @[id_col] is set and that column doesn't exist in @[record] 
//! then the field is added to the mapping with the value that the 
//! inserted or updated record got. 
//! 
//! @returns 
//! The value of the @[id_col] column for the new or updated record. 
//! Zero is returned if there is no @[id_col] column. 
//! 
//! @note 
//! This function isn't atomic if @[clear_other_fields] is unset and 
//! @[record] contains fields which do not correspond to real columns, 
//! i.e. if the @[prop_col] column may need to be updated. 
{ 
  return conn_insert_or_update (get_db(), record, clear_other_fields); 
} 
 
void delete (string|array where, void|string|array rest) 
//! Deletes records from the table that matches a condition. 
//! 
//! Both @[where] and @[rest] may be given as arrays to use bindings 
//! or @expr{sprintf@}-style formatting - see @[handle_argspec] for 
//! details. 
//! 
//! @param where 
//! The match condition, on the form of a WHERE expression. 
//! 
//! A WHERE clause will always be generated, but you can put e.g. 
//! "TRUE" in the match condition to select all records. 
//! 
//! @param rest 
//! Optional clauses that follows after the WHERE clause in a DELETE, 
//! i.e. ORDER BY and/or LIMIT. 
//! 
//! @seealso 
//! @[remove] 
//! 
//! @fixme 
//! Add support for joins. 
{ 
  conn_delete (get_db(), where, rest); 
} 
 
void remove (mixed id) 
//! Removes the record matched by the primary key value in @[id]. 
//! Nothing happens if there is no such record. 
//! 
//! If the table has a multicolumn primary key then @[id] must be an 
//! array which has the values for the primary key columns in the same 
//! order as @[pk_cols]. Otherwise @[id] is taken directly as the 
//! value of the single primary key column. 
//! 
//! @seealso 
//! @[remove_multi], @[delete] 
{ 
  conn_remove (get_db(), id); 
} 
 
void remove_multi (array(mixed) ids) 
//! Removes multiple records selected by primary key values. It is not 
//! an error if some of the @[ids] elements don't match any records. 
//! 
//! This function currently only works if the primary key is a single 
//! column. 
//! 
//! @seealso 
//! @[remove] 
{ 
  conn_remove_multi (get_db(), ids); 
} 
 
Result select (string|array where, void|array(string) fields, 
               void|string|array select_exprs, void|string table_refs, 
               void|string|array rest, void|string select_flags) 
//! Retrieves all records that matches a condition. 
//! 
//! This function sends a SELECT statement, and it gives full 
//! expressive power to send any SELECT that is based on this table. 
//! 
//! The only functionality this function adds over 
//! @[Sql.big_typed_query] is conversion of TIMESTAMP values (see the 
//! class doc), and the (optional) handling of arbitrary properties in 
//! addition to the SQL columns. @[fields] may list such properties, 
//! and they are returned alongside the real columns. Properties 
//! cannot be used in WHERE expressions etc, though. 
//! 
//! Joins with other tables are possible through @[table_refs], but 
//! property columns in those tables aren't decoded. 
//! 
//! @param where 
//! The match condition, on the form of a WHERE expression. It may be 
//! given as an array to use bindings or @expr{sprintf@}-style 
//! formatting - see @[handle_argspec] for details. 
//! 
//! A WHERE clause will always be generated, but you can put e.g. 
//! "TRUE" in the match condition to select all records. 
//! 
//! @param fields 
//! The fields to retrieve. All fields are retrieved if it's zero or 
//! left out. 
//! 
//! For columns, the result mappings always have corresponding 
//! entries. Other fields, i.e. properties, only occur in the result 
//! mappings when they match fields in the @[prop_col] column. 
//! 
//! A @expr{0@} (zero) entry can be used in @[fields] to return all 
//! properties without filtering. 
//! 
//! @param select_exprs 
//! Optional extra select expression besides the requested columns. 
//! This is just added to the list of selected columns, after a 
//! separating ",". 
//! 
//! @[select_exprs] may be given as an array to use bindings or 
//! @expr{sprintf@}-style formatting - see @[handle_argspec] for 
//! details. 
//! 
//! Note that expressions in @[select_exprs] that produce TIMESTAMP 
//! values are not converted to unix time integers - they are instead 
//! returned as formatted date/time strings. 
//! 
//! @param table_refs 
//! Optional other tables to join into the SELECT. This is inserted 
//! between "FROM @[table]" and "WHERE". 
//! 
//! @param rest 
//! Optional clauses that follows after the WHERE clause, e.g. ORDER 
//! BY, GROUP BY, and LIMIT. It may be given as an array to use 
//! bindings or @expr{sprintf@}-style formatting - see 
//! @[handle_argspec] for details. 
//! 
//! @param select_flags 
//! Flags for the SELECT statement. If this string is given, it is 
//! simply inserted directly after the "SELECT" keyword. 
//! 
//! @returns 
//! Returns a @[SqlTable.Result] object from which the results can be 
//! retrieved. Zero is never returned. 
//! 
//! @note 
//! The result object implements an iterator, so it can be used 
//! directly in e.g. a @expr{foreach@}. 
//! 
//! @note 
//! @[quote] may be used to quote string literals if the 
//! @expr{sprintf@}-style formats aren't used. 
//! 
//! @seealso 
//! @[select1], @[get], @[get_multi] 
{ 
  return conn_select (get_db(), where, fields, select_exprs, table_refs, 
                      rest, select_flags); 
} 
 
array select1 (string|array select_expr, string|array where, 
               void|string table_refs, void|string|array rest, 
               void|string select_flags) 
//! Convenience variant of @[select] for retrieving only a single 
//! column. The return value is an array containing the values in the 
//! @[select_expr] column. 
//! 
//! @param select_expr 
//! The field to retrieve. It may name a column or a property, or it 
//! may be a select expression like "SHA1(x)". It may be given as an 
//! array to use bindings or @expr{sprintf@}-style formatting - see 
//! @[handle_argspec] for details. 
//! 
//! @param where 
//! The match condition, on the form of a WHERE expression. A WHERE 
//! clause will always be generated, but you can put e.g. "TRUE" in 
//! the match condition to select all records. 
//! 
//! @[where] may be given as an array to use bindings or 
//! @expr{sprintf@}-style formatting - see @[handle_argspec] for 
//! details. 
//! 
//! @param table_refs 
//! Optional other tables to join into the SELECT. This is inserted 
//! between "FROM @[table]" and "WHERE". 
//! 
//! @param rest 
//! Optional clauses that follows after the WHERE clause, e.g. ORDER 
//! BY, GROUP BY, and LIMIT. It may be given as an array to use 
//! bindings or @expr{sprintf@}-style formatting - see 
//! @[handle_argspec] for details. 
//! 
//! @param select_flags 
//! Flags for the SELECT statement. If this string is given, it is 
//! simply inserted directly after the "SELECT" keyword. 
//! 
//! @returns 
//! Returns an array with the values in the selected column. If a 
//! property is retrieved and some rows don't have the wanted property 
//! then @[UNDEFINED] is put into those elements. 
//! 
//! @seealso 
//! @[select], @[get], @[get_multi] 
{ 
  return conn_select1 (get_db(), select_expr, where, table_refs, 
                       rest, select_flags); 
} 
 
mapping(string:mixed) get (mixed id, void|array(string) fields) 
//! Returns the record matched by a primary key value, or zero if 
//! there is no such record. 
//! 
//! @param id 
//! The value for the primary key. 
//! 
//! If the table has a multicolumn primary key then @[id] must be an 
//! array which has the values for the primary key columns in the same 
//! order as @[pk_cols]. Otherwise @[id] is taken directly as the 
//! value of the single primary key column. 
//! 
//! @param fields 
//! The fields to retrieve. All fields are retrieved if it's zero or 
//! left out. 
//! 
//! For columns, the result mappings always have corresponding 
//! entries. Other fields, i.e. properties, only occur in the result 
//! mappings when they match fields in the @[prop_col] column. 
//! 
//! A @expr{0@} (zero) entry can be used in @[fields] to return all 
//! properties without filtering. 
//! 
//! @seealso 
//! @[select], @[select1], @[get_multi] 
{ 
  return conn_get (get_db(), id, fields); 
} 
 
Result get_multi (array(mixed) ids, void|array(string) fields) 
//! Retrieves multiple records selected by primary key values. 
//! 
//! This function currently only works if the primary key is a single 
//! column. 
//! 
//! @param id 
//! Array containing primary key values. 
//! 
//! The number of returned records might be less than the number of 
//! entries here if some of them don't match any record. Also, the 
//! order of the returned records has no correlation to the order in 
//! the @[id] array. 
//! 
//! @param fields 
//! The fields to retrieve. All fields are retrieved if it's zero or 
//! left out. 
//! 
//! For columns, the result mappings always have corresponding 
//! entries. Other fields, i.e. properties, only occur in the result 
//! mappings when they match fields in the @[prop_col] column. 
//! 
//! A @expr{0@} (zero) entry can be used in @[fields] to return all 
//! properties without filtering. 
//! 
//! @returns 
//! Returns a @[SqlTable.Result] object from which the results can be 
//! retrieved. Zero is never returned. 
//! 
//! @note 
//! The result object implements an iterator, so it can be used 
//! directly in e.g. a @expr{foreach@}. 
//! 
//! @seealso 
//! @[get], @[select], @[select1] 
{ 
  return conn_get_multi (get_db(), ids, fields); 
} 
 
// Explicit connection handling. 
 
int conn_insert (Sql.Sql db_conn, mapping(string:mixed)... records) 
//! Like @[insert], but a database connection object is passed 
//! explicitly instead of being retrieved via @[get_db]. 
{ 
  Sql.mysql conn = db_conn; 
#ifdef MYSQL_DEBUG 
  if (!sizeof (records)) error ("Must give at least one record.\n"); 
#endif 
  UPDATE_MSG ("%O: insert %O\n", 
              this, sizeof (records) == 1 ? records[0] : records); 
  mapping(string:mixed) first_rec = records[0]; 
  conn->big_query ("INSERT `" + table + "` " + 
                   make_insert_clause (records), 
                   UNDEFINED, query_charset); 
  invalidate_cache(); 
  if (!id_col) return 0; 
  if (!has_index (first_rec, id_col)) 
    return first_rec[id_col] = conn->insert_id(); 
  else 
    return first_rec[id_col]; 
} 
 
int conn_insert_ignore (Sql.Sql db_conn, mapping(string:mixed)... records) 
//! Like @[insert_ignore], but a database connection object is passed 
//! explicitly instead of being retrieved via @[get_db]. 
{ 
  Sql.mysql conn = db_conn; 
#ifdef MYSQL_DEBUG 
  if (!sizeof (records)) error ("Must give at least one record.\n"); 
#endif 
  UPDATE_MSG ("%O: insert_ignore %O\n", 
              this, sizeof (records) == 1 ? records[0] : records); 
  mapping(string:mixed) first_rec = records[0]; 
  conn->big_query ("INSERT IGNORE `" + table + "` " + 
                   make_insert_clause (records), 
                   UNDEFINED, query_charset); 
  invalidate_cache(); 
  if (!id_col) return 0; 
  int last_insert_id = conn->insert_id(); 
  if (last_insert_id && 
      sizeof (records) == 1 && !has_index (first_rec, id_col)) 
    // Only set the field if we got a single record. Otherwise we 
    // don't really know which record it applies to. 
    first_rec[id_col] = last_insert_id; 
  return last_insert_id; 
} 
 
int conn_replace (Sql.Sql db_conn, mapping(string:mixed)... records) 
//! Like @[replace], but a database connection object is passed 
//! explicitly instead of being retrieved via @[get_db]. 
{ 
  Sql.mysql conn = db_conn; 
#ifdef MYSQL_DEBUG 
  if (!sizeof (records)) error ("Must give at least one record.\n"); 
#endif 
  UPDATE_MSG ("%O: replace %O\n", 
              this, sizeof (records) == 1 ? records[0] : records); 
  mapping(string:mixed) first_rec = records[0]; 
  conn->big_query ("REPLACE `" + table + "` " + 
                   make_insert_clause (records), 
                   UNDEFINED, query_charset); 
  invalidate_cache(); 
  if (!id_col) return 0; 
  if (!has_index (first_rec, id_col)) 
    return first_rec[id_col] = conn->insert_id(); 
  else 
    return first_rec[id_col]; 
} 
 
void conn_update (Sql.Sql db_conn, mapping(string:mixed) record, 
                  void|int(0..2) clear_other_fields) 
//! Like @[update], but a database connection object is passed 
//! explicitly instead of being retrieved via @[get_db]. 
{ 
  Sql.mysql conn = db_conn; 
#ifdef MYSQL_DEBUG 
  if (!(<0,1,2>)[clear_other_fields]) 
    error ("Invalid clear_other_fields flag.\n"); 
#endif 
  UPDATE_MSG ("%O: update%s %O\n", this, 
              clear_other_fields == 2 ? " (clear all other fields)" : 
              clear_other_fields == 1 ? " (clear other props)" : "", record); 
 
  record += ([]); 
  string pk_where = make_pk_where (record); 
  if (!pk_where) 
    error ("The record lacks a value for a primary key column.\n"); 
  record = update_pack_fields (conn, record, pk_where, clear_other_fields); 
 
  conn->big_query ("UPDATE `" + table + "` " 
                   "SET " + make_set_clause (record, 
                                             clear_other_fields == 2) + " " 
                   "WHERE " + pk_where + " " 
                   "LIMIT 1",       // The limit is just extra paranoia. 
                   UNDEFINED, query_charset); 
  invalidate_cache(); 
} 
 
int conn_insert_or_update (Sql.Sql db_conn, mapping(string:mixed) record, 
                           void|int(0..2) clear_other_fields) 
//! Like @[insert_or_update], but a database connection object is 
//! passed explicitly instead of being retrieved via @[get_db]. 
{ 
  Sql.mysql conn = db_conn; 
#ifdef MYSQL_DEBUG 
  if (!(<0,1,2>)[clear_other_fields]) 
    error ("Invalid clear_other_fields flag.\n"); 
#endif 
  UPDATE_MSG ("%O: insert_or_update%s %O\n", this, 
              clear_other_fields == 2 ? " (clear all other fields)" : 
              clear_other_fields == 1 ? " (clear other props)" : "", record); 
 
  // If we have properties to merge then do that with separate queries 
  // afterwards. We never do it by first querying the properties from 
  // an existing record (if any), even though that could save one 
  // query. That's because the race is less bothersome if we do it 
  // afterwards based on id_col than before based on pk_cols (or 
  // possibly all fields if pk_cols aren't given) - in the latter case 
  // we could retrieve the properties from a different record that got 
  // removed in the race window. Doing it afterwards might change the 
  // wrong record only if id_col isn't used. 
 
  mapping(string:mixed) real_cols = col_types & record; 
  mapping(string:mixed) other_fields = record - real_cols; 
  string prop_col_value; 
 
  if (sizeof (other_fields)) { 
#ifdef MYSQL_DEBUG 
    if (!prop_col) error ("Column(s) %s missing in table %O.\n", 
                          String.implode_nicely (indices (other_fields)), 
                          table); 
#endif 
    // These encoded properties are normally for the INSERT clause 
    // only - not used on update. That way we can avoid the two extra 
    // queries in the INSERT case, but otoh that query gets larger. 
    // It's used in both cases if clear_other_fields is set, though. 
    prop_col_value = get_and_merge_props (0, 0, other_fields); 
  } 
  else if (clear_other_fields && prop_col) 
    prop_col_value = ""; 
 
  array(string) update_set = allocate (sizeof (real_cols)); 
  { 
    int i; 
    foreach (real_cols; string col;) 
      update_set[i++] = "`" + col + "`=VALUES(`" + col + "`)"; 
  } 
 
  if (prop_col_value && !has_index (real_cols, prop_col)) { 
    if (clear_other_fields) 
      update_set += ({"`" + prop_col + "`=VALUES(`" + prop_col + "`)"}); 
    real_cols[prop_col] = prop_col_value; 
  } 
 
  if (id_col && !has_index (real_cols, id_col)) 
    update_set += ({"`" + id_col + "`=LAST_INSERT_ID(`" + id_col + "`)"}); 
 
  if (clear_other_fields == 2) { 
    foreach (col_types - real_cols - ({id_col}); string col;) 
      update_set += ({"`" + col + "`=DEFAULT(`" + col + "`)"}); 
  } 
 
  conn->big_query ("INSERT `" + table + "` " + 
                   make_insert_clause (({real_cols})) + " " + 
                   (sizeof (update_set) ? 
                    "ON DUPLICATE KEY UPDATE " + update_set * "," : ""), 
                   UNDEFINED, query_charset); 
 
  invalidate_cache(); 
 
  if (id_col && !has_index (record, id_col)) 
    record[id_col] = conn->insert_id(); 
 
  if (sizeof (other_fields) && !clear_other_fields && 
      // affected_rows() returns 2 if a record was updated, 1 if a new 
      // one was added, and 0 if nothing happened. We should merge in 
      // the property changes for both 2 and 0. 
      conn->affected_rows() != 1) { 
    string where = make_pk_where (record + ([])); 
    if (!where) { 
      // There's no AUTO_INCREMENT id column and the record doesn't 
      // contain values for the primary keys, so some of the columns 
      // matched an existing record through another unique index. 
      // Since we don't know which they are we have to match all the 
      // columns in the WHERE clause. FIXME: Add tracking of unique 
      // indices to avoid this. 
      String.Buffer buf = String.Buffer(); 
      int first = 1; 
      foreach (real_cols; string col_name; mixed val) 
        if (col_name != prop_col) { 
          if (first) first = 0; else buf->add (" AND "); 
          buf->add ("`", col_name, "`="); 
          add_mysql_value (buf, col_name, val); 
        } 
    } 
    update_props (conn, where, other_fields); 
  } 
 
  return id_col && record[id_col]; 
} 
 
void conn_delete (Sql.Sql db_conn, string|array where, void|string|array rest) 
//! Like @[delete], but a database connection object is passed 
//! explicitly instead of being retrieved via @[get_db]. 
{ 
  UPDATE_MSG ("%O: delete WHERE (%O)%s\n", this, where, 
              rest ? sprintf (" %O", rest) : ""); 
 
  mapping(string|int:mixed) bindings = ([]); 
  if (arrayp (where)) where = handle_argspec (where, bindings); 
  if (arrayp (rest)) rest = handle_argspec (rest, bindings); 
  if (!sizeof (bindings)) bindings = 0; 
 
  db_conn->big_query ("DELETE FROM `" + table + "` " 
                      "WHERE (" + where + ") " + (rest || ""), 
                      bindings); 
  invalidate_cache(); 
} 
 
void conn_remove (Sql.Sql db_conn, mixed id) 
//! Like @[remove], but a database connection object is passed 
//! explicitly instead of being retrieved via @[get_db]. 
{ 
  UPDATE_MSG ("%O: remove %O\n", this, id); 
  Sql.mysql conn = db_conn; 
  conn->big_query ("DELETE FROM `" + table + "` " 
                   "WHERE " + simple_make_pk_where (id), 
                   UNDEFINED, query_charset); 
  invalidate_cache(); 
} 
 
void conn_remove_multi (Sql.Sql db_conn, array(mixed) ids) 
//! Like @[remove_multi], but a database connection object is passed 
//! explicitly instead of being retrieved via @[get_db]. 
{ 
  UPDATE_MSG ("%O: remove_multi %{%O,%}\n", this, ids); 
  Sql.mysql conn = db_conn; 
  // FIXME: Split into several queries if the list is very long. 
  conn->big_query ("DELETE FROM `" + table + "` " 
                   "WHERE " + make_multi_pk_where (ids), 
                   UNDEFINED, query_charset); 
  invalidate_cache(); 
} 
 
Result conn_select (Sql.Sql db_conn, string|array where, 
                    void|array(string) fields, void|string|array select_exprs, 
                    void|string table_refs, void|string|array rest, 
                    void|string select_flags) 
//! Like @[select], but a database connection object is passed 
//! explicitly instead of being retrieved via @[get_db]. 
{ 
  mapping(string:mixed) bindings = ([]); 
  if (arrayp (where)) where = handle_argspec (where, bindings); 
  if (arrayp (select_exprs)) 
    select_exprs = handle_argspec (select_exprs, bindings); 
  if (arrayp (rest)) rest = handle_argspec (rest, bindings); 
  if (!sizeof (bindings)) bindings = 0; 
 
  Result res = Result(); 
 
  string query = "SELECT "; 
  if (select_flags) query += select_flags + " "; 
  query += res->prepare_select_expr (fields, select_exprs, !!table_refs) + 
    " FROM `" + table + "` " + (table_refs || ""); 
 
  res->res = db_conn->big_typed_query ( 
    query + " WHERE (" + where + ") " + (rest || ""), bindings); 
 
  return res; 
} 
 
array conn_select1 (Sql.Sql db_conn, string|array select_expr, 
                    string|array where, void|string table_refs, 
                    void|string|array rest, void|string select_flags) 
//! Like @[select1], but a database connection object is passed 
//! explicitly instead of being retrieved via @[get_db]. 
{ 
  mapping(string:mixed) bindings = ([]); 
  if (arrayp (select_expr)) 
    select_expr = handle_argspec (select_expr, bindings); 
  if (arrayp (where)) where = handle_argspec (where, bindings); 
  if (arrayp (rest)) rest = handle_argspec (rest, bindings); 
  if (!sizeof (bindings)) bindings = UNDEFINED; 
 
  string property; 
  string col_type = col_types[select_expr]; 
  if (!col_type && prop_col && 
      sscanf (select_expr, "%*[^ .(]%*1[ .(]") != 2) { 
    property = select_expr; 
    select_expr = prop_col; 
    col_type = "string"; 
  } 
 
  string query = "SELECT "; 
  if (select_flags) query += select_flags + " "; 
  if (timestamp_cols[select_expr]) 
    query += "UNIX_TIMESTAMP(`" + table + "`.`" + select_expr + "`)"; 
  else if (col_type) 
    query += "`" + table + "`.`" + select_expr + "`"; 
  else 
    query += select_expr; 
  query += " FROM `" + table + "` " + (table_refs || ""); 
 
  Sql.Result res = db_conn->big_typed_query ( 
    query + " WHERE (" + where + ") " + (rest || ""), bindings); 
 
#ifdef MYSQL_DEBUG 
  if (res->num_fields() != 1) 
    error ("Result from %O did not contain a single field (got %d fields).\n", 
           query, res->num_fields()); 
#endif 
 
  array ret = allocate (res->num_rows()); 
 
  if (property) { 
    int i = 0; 
    while (array(string) ent = res->fetch_row()) 
      ret[i++] = decode_props (ent[0], where)[property]; 
  } 
 
  else { 
    int i = 0; 
    while (array(mixed) ent = res->fetch_row()) { 
      ret[i++] = ent[0]; 
    } 
  } 
 
  return ret; 
} 
 
mapping(string:mixed) conn_get (Sql.Sql db_conn, mixed id, 
                                void|array(string) fields) 
//! Like @[get], but a database connection object is passed explicitly 
//! instead of being retrieved via @[get_db]. 
{ 
  Sql.mysql conn = db_conn; 
 
#ifdef MYSQL_DEBUG 
  if (fields && !sizeof (fields)) error ("No fields selected.\n"); 
#endif 
 
  int want_all = !fields; 
  if (want_all) { 
    if (prop_col) 
      // Some dwim: Probably don't want the prop_col value verbatim as 
      // well in the result. 
      fields = indices (col_types - ([prop_col: ""])); 
    else 
      fields = indices (col_types); 
  } 
 
  mapping(string:string) real_cols = col_types & fields; 
  mapping(string:string) other_fields; 
 
  if (sizeof (real_cols) < sizeof (fields)) { 
    if (!has_value (fields, 0)) { 
      mapping(string:string) field_map = mkmapping (fields, fields); 
      other_fields = field_map - real_cols; 
    } 
#ifdef MYSQL_DEBUG 
    if (!prop_col) 
      error ("Requested nonexisting column(s) %s.\n", 
             String.implode_nicely (indices (other_fields || 
                                             ([prop_col: ""])))); 
#endif 
  } 
  else if (!want_all) 
    other_fields = ([]); 
 
  int exclude_prop_col; 
  if (prop_col && !equal (other_fields, ([]))) { 
    if (!real_cols[prop_col]) exclude_prop_col = 1; 
    real_cols[prop_col] = "string"; 
  } 
 
  array(string) real_col_names = indices (real_cols); 
  array(string) real_col_types = values (real_cols); 
 
  array(string) select_cols = allocate (sizeof (real_col_types)); 
  foreach (real_col_names; int i; string name) { 
    if (timestamp_cols[name]) 
      select_cols[i] = "UNIX_TIMESTAMP(`" + name + "`)"; 
    else 
      select_cols[i] = "`" + name + "`"; 
  } 
 
  string pk_where = simple_make_pk_where (id); 
  Sql.Result res = 
    conn->big_typed_query ("SELECT " + (select_cols * ",") + " " 
                           "FROM `" + table + "` " 
                           "WHERE " + pk_where, 
                           0, query_charset); 
 
  array(string) ent = res->fetch_row(); 
  if (!ent) return 0; 
 
  mapping(string:mixed) rec = ([]); 
 
  foreach (ent; int i; string|int|float|Sql.Null val) { 
    rec[real_col_names[i]] = val; 
  } 
 
  if (prop_col && !equal (other_fields, ([]))) { 
    string prop_val = rec[prop_col]; 
    if (prop_val != 0 && prop_val != "") { 
      mapping(string:mixed) props = decode_props (prop_val, pk_where); 
      if (other_fields) props = other_fields & props; 
      // Properties take precedence over columns. That allows gradual 
      // migration to columns, since the field in prop_col will 
      // disappear in the next update. 
      rec += props; 
    } 
    if (exclude_prop_col) m_delete (rec, prop_col); 
  } 
 
  return rec; 
} 
 
Result conn_get_multi (Sql.Sql db_conn, array(mixed) ids, 
                       void|array(string) fields) 
//! Like @[get_multi], but a database connection object is passed 
//! explicitly instead of being retrieved via @[get_db]. 
{ 
  Sql.mysql conn = db_conn; 
  Result res = Result(); 
  // FIXME: Split into several queries if the list is very long. 
  res->res = 
    conn->big_typed_query ("SELECT " + 
                           res->prepare_select_expr (fields, 0, 0) + 
                           " FROM `" + table + "` " 
                           "WHERE " + make_multi_pk_where (ids), 
                           0, query_charset); 
  return res; 
} 
 
// The Result object. 
 
class Result 
//! Result object returned by e.g. @[select]. This is similar in 
//! function to an @[Sql.sql_result] object. It also implements the 
//! iterator interface and can therefore be used directly in e.g. 
//! @expr{foreach@}. 
{ 
  Sql.Result res; 
  //! The underlying result object from the db connection. 
 
  protected array(string) real_col_names; 
  // The names of the sql columns to retrieve. Initially this contains 
  // only the column names built from fields, not the names of the 
  // user supplied select expressions. The latter are added when the 
  // first row is fetched. 
  // 
  // If properties are being fetched but not the property column 
  // itself then real_col_names has a zero in the prop_pos position. 
 
  protected int add_select_expr_names; 
  // Nonzero if there are user supplied select expressions and their 
  // names have not yet been added to real_col_names. 
 
  protected int prop_pos; 
  // Position of the prop_col values in the result arrays, or -1 if we 
  // shouldn't handle that. 
 
  protected mapping(string:string) other_fields; 
  // Selected fields in the prop_col values, or zero if everything 
  // is wanted. The values are insignificant. 
 
  protected int cur_row; 
  protected mapping(string:mixed) cur_rec; 
  // Need to store the last fetched result for the iterator interface 
  // since fetch() advances the cursor, while the iterator's index() 
  // and value() must not. These are updated by fetch(), and cur_row 
  // is the row index of cur_rec, _not_ the next one. 
 
  protected string _sprintf (int flag) 
  { 
    return flag == 'O' && 
      sprintf ("SqlTable.Result(%O, %d/%d)", 
               global::this && table, cur_row, res && res->num_rows()); 
  } 
 
  int num_rows() {return res->num_rows();} 
  //! Returns the number of rows in the result. 
 
  int eof() {return res->eof();} 
  //! Returns nonzero if there are no more rows. 
 
  array(mapping(string:mixed)) column_info() {return res->fetch_fields();} 
  //! Returns information about the columns in the result. 
 
  mapping(string:mixed) fetch() 
  //! Fetches the next record from the result and advance the cursor. 
  //! Returns zero if there are no more records. 
  //! 
  //! The record is returned as a mapping. It is similar to the 
  //! mappings returned by @[Sql.query], except that native pike types 
  //! and @[Val.null] are used. If @[prop_col] is used then properties 
  //! from that column can be returned as mapping entries alongside 
  //! the columns, and those values can be any pike data type. 
  //! 
  //! As opposed to the @[Sql.query] mappings, the returned mapping 
  //! has a single entry for each field - there are no duplicate 
  //! entries prefixed with the table name. 
  { 
    if (cur_rec) cur_row++; 
 
    array(string) ent = res->fetch_row(); 
    if (!ent) return cur_rec = 0; 
 
    mapping(string:mixed) rec; 
 
    if (add_select_expr_names) { 
      // Fetch the names of the user supplied select expressions from 
      // the result. 
      array(mapping(string:mixed)) field_info = 
        res->fetch_fields()[sizeof (real_col_names)..]; 
      real_col_names += column (field_info, "name"); 
      add_select_expr_names = 0; 
    } 
 
    rec = mkmapping (real_col_names, ent); 
 
    if (prop_pos != -1) { 
      m_delete (rec, 0); 
      if (!(<0, "">)[ent[prop_pos]]) { 
        mapping(string:mixed) props = decode_props (ent[prop_pos], 0); 
        if (other_fields) props = other_fields & props; 
        // Properties take precedence over columns. That allows 
        // gradual migration to columns, since the field in prop_col 
        // will disappear in the next update. 
        rec += props; 
      } 
    } 
 
    return cur_rec = rec; 
  } 
 
  array(mapping(string:mixed)) get_array() 
  //! Returns all the remaining records as an array of mappings. 
  //! @[eof] returns true after this. 
  //! 
  //! @note 
  //! This is not a cast since it destructively modifies this object 
  //! by fetching all remaining records. 
  { 
    array(mapping(string:mixed)) res = ({}); 
    while (mapping(string:mixed) rec = fetch()) 
      res += ({rec}); 
    return res; 
  } 
 
  string prepare_select_expr (array(string) fields, string select_exprs, 
                              int with_table_qualifiers) 
  // Internal function to initialize all the variables from an 
  // optional array of requested fields. 
  { 
#ifdef MYSQL_DEBUG 
    if (fields && !sizeof (fields)) error ("No fields selected.\n"); 
#endif 
 
    string select_clause; 
    string tbl_qual = with_table_qualifiers ? table + "`.`" : ""; 
    int want_all = !fields; 
 
    prop_pos = -1; 
 
    if (want_all) { 
      if (prop_col) 
        // Some dwim: Probably don't want the prop_col value verbatim 
        // as well in the result. 
        fields = indices (col_types - ([prop_col: ""])); 
      else 
        fields = indices (col_types); 
    } 
 
    mapping(string:string) real_cols = col_types & fields; 
    if (sizeof (real_cols)) { 
      mapping(string:int(1..1)) ts_cols = timestamp_cols & fields; 
      if (sizeof (ts_cols)) { 
        real_col_names = indices (ts_cols); 
        select_clause = 
          "UNIX_TIMESTAMP(`" + tbl_qual + 
          (real_col_names * ("`),UNIX_TIMESTAMP(`" + tbl_qual)) + "`)"; 
        if (sizeof (ts_cols) < sizeof (real_cols)) { 
          array(string) normal_col_names = indices (real_cols - ts_cols); 
          real_col_names += normal_col_names; 
          select_clause += 
            ",`" + tbl_qual + (normal_col_names * ("`,`" + tbl_qual)) + "`"; 
        } 
      } 
      else { 
        real_col_names = indices (real_cols); 
        select_clause = 
          "`" + tbl_qual + (real_col_names * ("`,`" + tbl_qual)) + "`"; 
      } 
    } else { 
      real_col_names = ({}); 
    } 
 
    if (sizeof (real_cols) < sizeof (fields)) { 
      if (!has_value (fields, 0)) { 
        mapping(string:string) field_map = mkmapping (fields, fields); 
        other_fields = field_map - real_cols; 
      } 
#ifdef MYSQL_DEBUG 
      if (!prop_col) 
        error ("Requested nonexisting column(s) %s.\n", 
               String.implode_nicely (indices (other_fields || 
                                               ([prop_col: ""])))); 
#endif 
    } 
    else if (!want_all) 
      other_fields = ([]); 
 
    if (prop_col && !equal (other_fields, ([]))) { 
      if (real_cols[prop_col]) 
        prop_pos = search (real_col_names, prop_col); 
      else { 
        prop_pos = sizeof (real_col_names); 
        if (select_clause) select_clause += ",`" + tbl_qual + prop_col + "`"; 
        else select_clause = "`" + tbl_qual + prop_col + "`"; 
        real_col_names += ({0}); 
      } 
    } 
 
    if (select_exprs) { 
      add_select_expr_names = 1; 
      if (select_clause) select_clause += ", " + select_exprs; 
      else select_clause = select_exprs; 
    } 
 
    return select_clause || ""; 
  } 
 
  // Iterator interface. This is a separate object only to avoid 
  // implementing a `! in Result, which would make it behave oddly. 
 
#ifdef MYSQL_DEBUG 
  protected int got_iterator; 
#endif 
 
  Iterator _get_iterator() 
  //! Returns an iterator for the result. Only one iterator may be 
  //! created per @[Result] object. 
  { 
#ifdef MYSQL_DEBUG 
    if (got_iterator) 
      error ("Cannot create more than one iterator for a Result object.\n"); 
    got_iterator = 1; 
#endif 
    return Iterator (num_rows()); 
  } 
 
  protected class Iterator (protected int cached_num_rows) 
  { 
    protected int `!() {return cur_row >= cached_num_rows;} 
    protected int _sizeof() {return cached_num_rows;} 
 
    protected string _sprintf (int flag) 
    { 
      return flag == 'O' && 
        sprintf ("SqlTable.Result.Iterator(%O, %d/%d)", 
                 Result::this && global::this && table, 
                 Result::this && cur_row, cached_num_rows); 
    } 
 
    int index() 
    { 
      return cur_row < cached_num_rows ? cur_row : UNDEFINED; 
    } 
 
    mapping(string:mixed) value() 
    { 
      if (!cur_rec) fetch(); 
      return cur_row < cached_num_rows ? cur_rec : UNDEFINED; 
    } 
 
    int next() 
    { 
      fetch(); 
      return cur_row < cached_num_rows; 
    } 
 
    protected Iterator `+= (int steps) 
    // Old interface for pike 7.4 compat. 
    { 
      if (steps < 0) error ("Stepping backwards not supported.\n"); 
      while (steps--) if (!next()) break; 
      return this; 
    } 
  } 
} 
 
// Internals. 
 
protected string format_rec_compact (mapping(string:mixed) rec) 
{ 
  array(string) vars = indices (rec); 
  array(mixed) vals = values (rec); 
  sort (vars, vals); 
  array(string) rows = allocate (sizeof (vars)); 
  foreach (vals; int i; mixed val) { 
    if (stringp (val) || arrayp (val) || mappingp (val)) 
      rows[i] = sprintf ("  %O: %t[%d],\n", vars[i], val, sizeof (val)); 
    else 
      rows[i] = sprintf ("  %O: %O,\n", vars[i], val); 
  } 
  return "([\n" + rows * "" + "])"; 
} 
 
protected mapping(string:mixed) decode_props (string prop_val, string where) 
{ 
  if (prop_val != 0 && prop_val != "") { 
    mixed decoded; 
    mixed err = catch (decoded = decode_value (prop_val)); 
    if (err || !mappingp (decoded)) 
      // This is bad, but the best we can do is to report it on stderr 
      // and continue so that the bogus value gets flushed out and the 
      // app can recover somewhat. FIXME: Maybe add a flag to control 
      // what to do here. 
      werror ("WARNING! Failed to decode property value " 
              "in `%s` from `%s`%s: %s" 
              "The garbled property value is: %O\n" 
              "It will be ignored and overwritten.\n", 
              prop_col, table, where ? " where " + where : "", 
              (err ? describe_error (err) : 
               sprintf ("Expected mapping, got %O.\n", decoded)), 
              prop_val); 
    else 
      return [mapping(string:mixed)] decoded; 
  } 
  return ([]); 
} 
 
protected void add_mysql_value (String.Buffer buf, string col_name, mixed val) 
// An undefined value is formatted as "DEFAULT". 
{ 
  if (stringp (val)) { 
#ifdef MYSQL_DEBUG 
    if (col_types[col_name] != "string") 
      error ("Got string value %q for %s column `%s`.\n", 
             val, col_types[col_name], col_name); 
#endif 
    if (String.width (val) == 8) 
      // _latin1 works fine for binary data since the actual charset 
      // isn't significant. The only problem is for 8-bit text where 
      // mysql latin1 has chars in the control range 0x80..0x9f. Since 
      // those control chars are very uncommon in text we just ignore 
      // that problem for now. 
      buf->add ("_latin1\"", quote (val), "\""); 
    else 
      // FIXME: If the column holds binary data we should throw an 
      // error here instead of sending what is effectively garbled 
      // data. 
      buf->add ("_utf8\"", string_to_utf8 (quote (val), 2), "\""); 
  } 
  else if (intp (val)) { 
    if (undefinedp (val)) 
      buf->add ("DEFAULT"); 
    else { 
#ifdef MYSQL_DEBUG 
      if (col_types[col_name] != "int" && !datetime_cols[col_name]) 
        error ("Got integer value %O for %s column `%s`.\n", 
               val, col_types[col_name] || "string", col_name); 
#endif 
      if (timestamp_cols[col_name]) 
        buf->add ("FROM_UNIXTIME(", (string) val, ")"); 
      else 
        buf->add ((string) val); 
    } 
  } 
  else if (val == Val.null) 
    buf->add ("NULL"); 
  else { 
#ifdef MYSQL_DEBUG 
    if (objectp (val) && functionp (val->den)) { 
      // Allow Gmp.mpq for float fields, and for int fields if they 
      // have no fractional part. 
      if (col_types[col_name] != "float" && 
          !(val->den() == 1 && col_types[col_name] == "int")) 
        error ("Got %O for %s column `%s`.\n", 
               val, col_types[col_name] || "string", col_name); 
    } 
    else { 
      if (!floatp (val)) 
        error ("Cannot use %t value for `%s`: %O\n", val, col_name, val); 
      if (col_types[col_name] != "float") 
        error ("Got float value %O for %s column `%s`.\n", 
               val, col_types[col_name] || "string", col_name); 
    } 
#endif 
    buf->add ((string) val); 
  } 
} 
 
protected string make_insert_clause (array(mapping(string:mixed)) records) 
// Returns an "(a,b,c) VALUES (1,2,3),(4,5,6)" clause as used in 
// INSERT statements. Fields that don't have columns are packed into 
// prop_col updates. Destructive on the records array, but not on the 
// mapping elements. 
{ 
  mapping(string:mixed) query_cols = ([]); // Only indices are relevant. 
 
  // FIXME: Ought to use bindings, but Mysql.mysql doesn't support it 
  // yet (as of pike 7.8.191). 
 
#ifdef MYSQL_DEBUG 
  if (!sizeof (records)) error ("Must give at least one record.\n"); 
#endif 
 
  foreach (records; int i; mapping(string:mixed) rec) { 
    mapping(string:mixed) real_cols = col_types & rec; 
    mapping(string:mixed) other_fields = rec - real_cols; 
 
    if (sizeof (other_fields)) { 
#ifdef MYSQL_DEBUG 
      if (!prop_col) error ("Column(s) %s missing.\n", 
                            String.implode_nicely (indices (other_fields))); 
#endif 
 
      string encoded_props; 
      if (mixed err = catch { 
          encoded_props = encode_value_canonic (other_fields); 
        }) 
        error ("Failed to encode properties: %sThe properties are: %O\n", 
               describe_error (err), other_fields); 
 
      if (sizeof (encoded_props) > prop_col_max_length) 
        error ("Property value too long (%d b - max is %d b) " 
               "for `%s` in `%s` - failed to insert record: %s\n", 
               sizeof (encoded_props), prop_col_max_length, prop_col, table, 
               format_rec_compact (rec)); 
      real_cols[prop_col] = encoded_props; 
    } 
 
    query_cols |= real_cols; 
    records[i] = real_cols; 
  } 
 
  array(string) col_list = indices (query_cols); 
  String.Buffer buf = String.Buffer(); 
  if (sizeof (col_list)) 
    buf->add ("(`", (col_list * "`,`"), "`) VALUES "); 
  else 
    buf->add ("() VALUES "); 
 
  int first = 1; 
  foreach (records, mapping(string:mixed) rec) { 
    if (first) first = 0; else buf->add (","); 
    buf->add ("("); 
 
    int col_first = 1; 
    foreach (map (col_list, rec); int i; mixed val) { 
      if (col_first) col_first = 0; else buf->add (","); 
      add_mysql_value (buf, col_list[i], val); 
    } 
 
    buf->add (")"); 
  } 
 
  return buf->get(); 
} 
 
protected string make_pk_where (mapping(string:mixed) rec) 
// Returns a WHERE expression like "a=1 AND b=2" for matching the 
// primary key, or zero if the record doesn't have values for all pk 
// columns. The pk fields are also removed from the rec mapping. 
{ 
#ifdef MYSQL_DEBUG 
  if (!sizeof (pk_cols)) error ("There is no primary key in this table.\n"); 
#endif 
  String.Buffer buf = String.Buffer(); 
  int first = 1; 
  foreach (pk_cols, string pk_col) { 
    if (first) first = 0; else buf->add (" AND "); 
    mixed val = m_delete (rec, pk_col); 
    if (undefinedp (val) || val == Val.null) 
      return 0; 
    buf->add ("`", pk_col, "`="); 
    add_mysql_value (buf, pk_col, val); 
  } 
  return buf->get(); 
} 
 
protected string simple_make_pk_where (mixed id) 
// Returns a WHERE expression like "a=1 AND b=2" for matching the 
// primary key. id is like the argument to get(). 
{ 
#ifdef MYSQL_DEBUG 
  if (!sizeof (pk_cols)) error ("There is no primary key in this table.\n"); 
#endif 
 
  String.Buffer buf = String.Buffer(); 
  if (sizeof (pk_cols) == 1) { 
    buf->add ("`", pk_cols[0], "`="); 
#ifdef MYSQL_DEBUG 
    if (id == Val.null) 
      error ("Cannot use Val.null for primary key column %O.\n", 
             pk_cols[0]); 
#endif 
    add_mysql_value (buf, pk_cols[0], 
                     id || 0); // Clear any zero_type in id. 
  } 
 
  else { 
#ifdef MYSQL_DEBUG 
    if (!arrayp (id) || sizeof (id) != sizeof (pk_cols)) 
      error ("The id must be an array with %d elements.\n", sizeof (pk_cols)); 
#endif 
    int first = 1; 
    foreach (pk_cols; int i; string pk_col) { 
      if (first) first = 0; else buf->add (" AND "); 
      buf->add ("`", pk_cols[0], "`="); 
#ifdef MYSQL_DEBUG 
      if (id[i] == Val.null) 
        error ("Cannot use Val.null for primary key column %O.\n", pk_col); 
#endif 
      add_mysql_value (buf, pk_col, 
                       id[i] || 0); // Clear any zero_type in id[i]. 
    } 
  } 
 
  return buf->get(); 
} 
 
protected string make_multi_pk_where (array(mixed) ids, int|void negated) 
// Returns a WHERE expression like "foo IN (2,3,17,4711)" for matching 
// a bunch of records by primary key. 
{ 
#ifdef MYSQL_DEBUG 
  if (sizeof (pk_cols) != 1) 
    error ("The table must have a single column primary key.\n"); 
#endif 
 
  if (!sizeof (ids)) return negated?"TRUE":"FALSE"; 
 
  string pk_col = pk_cols[0]; 
  string pk_type = col_types[pk_col]; 
 
  string optional_not = negated?" NOT ":""; 
 
  if ((<"float", "int">)[pk_type]) { 
#ifdef MYSQL_DEBUG 
    foreach (ids; int i; mixed id) 
      if (!intp (id) && !floatp (id)) 
        error ("Expected numeric value for primary key column %O, " 
               "got %t at position %d.\n", 
               pk_col, id, i); 
#endif 
    return (timestamp_cols[pk_col] ? 
            "UNIX_TIMESTAMP(`" + pk_col + "`)" : "`" + pk_col + "`") + 
      optional_not + " IN (" + (((array(string)) ids) * ",") + ")"; 
  } 
 
  else { 
#ifdef MYSQL_DEBUG 
    foreach (ids; int i; mixed id) 
      if (!stringp (id)) 
        error ("Expected string value for primary key column %O, " 
               "got %t at position %d.\n", 
               pk_col, id, i); 
#endif 
    String.Buffer buf = String.Buffer(); 
    buf->add ("`", pk_col, "` ", optional_not, " IN ("); 
    int first = 1; 
    foreach (ids, string id) { 
      if (first) first = 0; else buf->add (","); 
      add_mysql_value (buf, pk_col, id); 
    } 
    buf->add (")"); 
    return buf->get(); 
  } 
} 
 
protected string get_and_merge_props (Sql.mysql conn, string pk_where, 
                                      mapping(string:mixed) prop_changes) 
// Retrieves the current properties for a record (if pk_where is set), 
// merges prop_changes into them, and returns the new value to assign 
// to the properties column. 
{ 
  mapping(string:mixed) old_props; 
  if (array(string) ent = pk_where && 
      conn->big_query ("SELECT `" + prop_col + "` " 
                       "FROM `" + table + "` " 
                       "WHERE " + pk_where, 
                       UNDEFINED, query_charset)->fetch_row()) 
    old_props = decode_props (ent[0], pk_where); 
  else 
    old_props = ([]); 
 
  mapping(string:mixed) rem_props = filter (prop_changes, `==, Val.null); 
  mapping(string:mixed) new_props = old_props + prop_changes - rem_props; 
 
  string encoded_props; 
  if (mixed err = catch { 
      encoded_props = encode_value_canonic (new_props); 
    }) 
    error ("Failed to encode properties: %sThe properties are: %O\n", 
           describe_error (err), new_props); 
 
  if (sizeof (encoded_props) > prop_col_max_length) 
    error ("Property value too long (%d b - max is %d b) " 
           "for `%s` in `%s`%s: %s", 
           sizeof (encoded_props), prop_col_max_length, 
           prop_col, table, pk_where ? " where " + pk_where : "", 
           format_rec_compact (new_props)); 
 
  return encoded_props; 
} 
 
protected void update_props (Sql.mysql conn, string pk_where, 
                             mapping(string:mixed) prop_changes) 
// Updates the properties column by retrieving the current properties 
// and merging prop_changes into them. prop_changes is assumed to only 
// contain properties. 
{ 
  string encoded_props = get_and_merge_props (conn, pk_where, prop_changes); 
  conn->big_query ("UPDATE `" + table + "` " 
                   "SET `" + prop_col + "`=" 
                   "_binary\"" + quote (encoded_props) + "\" " 
                   "WHERE " + pk_where + " " 
                   "LIMIT 1",       // In case the WHERE condition is bad. 
                   UNDEFINED, query_charset); 
} 
 
protected mapping(string:mixed) update_pack_fields ( 
  Sql.mysql conn, mapping(string:mixed) rec, string pk_where, 
  int replace_properties) 
// Returns a record mapping where all fields that don't have columns 
// have been packed into a prop_col entry. The table is queried if 
// necessary to obtain the old prop_col fields for merging. 
{ 
  mapping(string:mixed) real_cols = col_types & rec; 
  mapping(string:mixed) other_fields = rec - real_cols; 
 
  if (sizeof (other_fields)) { 
#ifdef MYSQL_DEBUG 
    if (!prop_col) error ("Column(s) %s missing in table %O.\n", 
                          String.implode_nicely (indices (other_fields)), 
                          table); 
#endif 
    if (replace_properties) pk_where = 0; 
    else if (!pk_where) pk_where = make_pk_where (rec + ([])); 
    real_cols[prop_col] = get_and_merge_props (conn, pk_where, other_fields); 
  } 
 
  else if (replace_properties && prop_col) 
    real_cols[prop_col] = ""; 
 
  return real_cols; 
} 
 
protected string make_set_clause (mapping(string:mixed) rec, 
                                  int set_all_columns) 
// Returns a SET clause like "a=1,b=2" as is used in an UPDATE 
// statement. All fields are assumed to have columns. If 
// set_all_columns is given then all unmentioned columns, except the 
// primary key columns, are set to their default values. 
{ 
  String.Buffer buf = String.Buffer(); 
 
  int first = 1; 
  foreach (rec; string col; mixed val) { 
    if (first) first = 0; else buf->add (","); 
    buf->add ("`", col, "`="); 
    add_mysql_value (buf, col, val); 
  } 
 
  if (set_all_columns) 
    foreach (col_types - rec - pk_cols; string col;) { 
      if (first) first = 0; else buf->add (","); 
      buf->add ("`", col, "`=DEFAULT(`", col, "`)"); 
    } 
 
  return buf->get(); 
} 
 
protected int _sizeof() 
{ 
  int ret = num_entries; 
  if (ret < 0) { 
    // NB: Thread safe! 
    ret = num_entries = (int)(select1("COUNT(*)", "TRUE")[0]); 
  } 
  return ret; 
}