Search moodle.org's
Developer Documentation

See Release Notes
Long Term Support Release

  • Bug fixes for general core bugs in 4.1.x will end 13 November 2023 (12 months).
  • Bug fixes for security issues in 4.1.x will end 10 November 2025 (36 months).
  • PHP version: minimum PHP 7.4.0 Note: minimum PHP version has increased since Moodle 4.0. PHP 8.0.x is supported too.
/lib/ddl/ -> postgres_sql_generator.php (source)

[Source view]

PostgreSQL specific SQL code generator.

Copyright: 1999 onwards Martin Dougiamas http://dougiamas.com
License: http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
File Size: 520 lines (24 kb)
Included or required:0 times
Referenced: 0 times
Includes or requires: 0 files

Defines 1 class

postgres_sql_generator:: (13 methods):
  getResetSequenceSQL()
  getCreateTempTableSQL()
  getCreateIndexSQL()
  getTypeSQL()
  getCommentSQL()
  getRenameTableExtraSQL()
  getAlterFieldSQL()
  getCreateDefaultSQL()
  getDropDefaultSQL()
  addslashes()
  getSequenceFromDB()
  isNameInUse()
  getReservedWords()


Class: postgres_sql_generator  - X-Ref

This class generate SQL code to be used against PostgreSQL
It extends XMLDBgenerator so everything can be
overridden as needed to generate correct SQL.

getResetSequenceSQL($table)   X-Ref
Reset a sequence to the id field of a table.

param: xmldb_table|string $table name of table or the table object.
return: array of sql statements

getCreateTempTableSQL($xmldb_table)   X-Ref
Given one correct xmldb_table, returns the SQL statements
to create temporary table (inside one array).

param: xmldb_table $xmldb_table The xmldb_table object instance.
return: array of sql statements

getCreateIndexSQL($xmldb_table, $xmldb_index)   X-Ref
Given one correct xmldb_index, returns the SQL statements
needed to create it (in array).

param: xmldb_table $xmldb_table The xmldb_table instance to create the index on.
param: xmldb_index $xmldb_index The xmldb_index to create.
return: array An array of SQL statements to create the index.

getTypeSQL($xmldb_type, $xmldb_length=null, $xmldb_decimals=null)   X-Ref
Given one XMLDB Type, length and decimals, returns the DB proper SQL type.

param: int $xmldb_type The xmldb_type defined constant. XMLDB_TYPE_INTEGER and other XMLDB_TYPE_* constants.
param: int $xmldb_length The length of that data type.
param: int $xmldb_decimals The decimal places of precision of the data type.
return: string The DB defined data type.

getCommentSQL($xmldb_table)   X-Ref
Returns the code (array of statements) needed to add one comment to the table.

param: xmldb_table $xmldb_table The xmldb_table object instance.
return: array Array of SQL statements to add one comment to the table.

getRenameTableExtraSQL($xmldb_table, $newname)   X-Ref
Returns the code (array of statements) needed to execute extra statements on table rename.

param: xmldb_table $xmldb_table The xmldb_table object instance.
param: string $newname The new name for the table.
return: array Array of extra SQL statements to rename a table.

getAlterFieldSQL($xmldb_table, $xmldb_field, $skip_type_clause = NULL, $skip_default_clause = NULL, $skip_notnull_clause = NULL)   X-Ref
Given one xmldb_table and one xmldb_field, return the SQL statements needed to alter the field in the table.

PostgreSQL has some severe limits:
- Any change of type or precision requires a new temporary column to be created, values to
be transfered potentially casting them, to apply defaults if the column is not null and
finally, to rename it
- Changes in null/not null require the SET/DROP NOT NULL clause
- Changes in default require the SET/DROP DEFAULT clause

param: xmldb_table $xmldb_table The table related to $xmldb_field.
param: xmldb_field $xmldb_field The instance of xmldb_field to create the SQL from.
param: string $skip_type_clause The type clause on alter columns, NULL by default.
param: string $skip_default_clause The default clause on alter columns, NULL by default.
param: string $skip_notnull_clause The null/notnull clause on alter columns, NULL by default.
return: string The field altering SQL statement.

getCreateDefaultSQL($xmldb_table, $xmldb_field)   X-Ref
Given one xmldb_table and one xmldb_field, return the SQL statements needed to add its default
(usually invoked from getModifyDefaultSQL()

param: xmldb_table $xmldb_table The xmldb_table object instance.
param: xmldb_field $xmldb_field The xmldb_field object instance.
return: array Array of SQL statements to create a field's default.

getDropDefaultSQL($xmldb_table, $xmldb_field)   X-Ref
Given one xmldb_table and one xmldb_field, return the SQL statements needed to drop its default
(usually invoked from getModifyDefaultSQL()

Note that this method may be dropped in future.

param: xmldb_table $xmldb_table The xmldb_table object instance.
param: xmldb_field $xmldb_field The xmldb_field object instance.
return: array Array of SQL statements to create a field's default.

addslashes($s)   X-Ref
Adds slashes to string.

param: string $s
return: string The escaped string.

getSequenceFromDB($xmldb_table)   X-Ref
Given one xmldb_table returns one string with the sequence of the table
in the table (fetched from DB)
The sequence name for Postgres has one standard name convention:
tablename_fieldname_seq
so we just calculate it and confirm it's present in pg_class

param: xmldb_table $xmldb_table The xmldb_table object instance.
return: string|bool If no sequence is found, returns false

isNameInUse($object_name, $type, $table_name)   X-Ref
Given one object name and it's type (pk, uk, fk, ck, ix, uix, seq, trg).

(MySQL requires the whole xmldb_table object to be specified, so we add it always)

This is invoked from getNameForObject().
Only some DB have this implemented.

param: string $object_name The object's name to check for.
param: string $type The object's type (pk, uk, fk, ck, ix, uix, seq, trg).
param: string $table_name The table's name to check in
return: bool If such name is currently in use (true) or no (false)

getReservedWords()   X-Ref
Returns an array of reserved words (lowercase) for this DB

return: array An array of database specific reserved words