Manual:SelectQueryBuilder.php
MediaWiki file: SelectQueryBuilder.php | |
---|---|
Location: | includes/libs/rdbms/querybuilder/ |
Source code: | master • 1.42.1 • 1.41.2 • 1.39.8 |
Classes: | Wikimedia\Rdbms\SelectQueryBuilder |
Class for building a SQL query and fetching its results, largely intended to be extended by more specialised classes. Extends JoinGroupBase .
Public methods
editNone of the methods in this class are stable to override.
- connection( IDatabase $db )
- queryInfo()
- rawTables()
- newSubquery()
Query methods
edit- from() - single table to the SELECT query. Alias for JoinGroupBase::table().
- tables() - Add multiple tables. It's recommended to use join() and leftJoin() instead in new code.
- field() - add a single field to the query, optionally with an alias. The field is an SQL fragment. It is unsafe to pass user input to this function.
- fields() - add a field or an array of fields to the query. Each field is an SQL fragment. If the array key is non-numeric, the key is taken to be an alias for the field.
- select() - alias for fields()
- where() - add conditions to the query. The supplied conditions will be appended to the existing conditions, separated by AND.
- andWhere() - alias.
- conds() - another alias.
- JOIN:
- join() - inherited from JoinGroupBase - join (INNER JOIN) a table or group of tables. To be called after from()/table().
- leftjoin() - inherited from JoinGroupBase - left join a table or group of tables. To be called after from().
- straightJoin() - inherited from JoinGroupBase - straight join a table or group of tables. To be called after from(). See also straightJoinOption() below.
- joinConds() - It's recommended to use join() and leftJoin() instead in new code.
- newJoinGroup() - create a parenthesized group of joins which can be added to the object like a table. The group is initially empty.
- offset() - set the offset. Skip this many rows at the start of the result set. Offset with limit() can theoretically be used for paging through a result set, but this is discouraged for performance reasons.
- limit()
- options:
- distinct()
- lockInShareMode()
- forUpdate()
- setMaxExecutionTime()
- clauses:
- groupBy() - add a GROUP BY clause. May be either an SQL fragment string naming a field or expression to group by, or an array of such SQL fragments. If there is an existing GROUP BY clause, the new one will be appended.
- having()
- orderBy()
- Index options
- useIndex()
- ignoreIndex()
- explain() - make the query be an EXPLAIN SELECT query instead of a SELECT query.
- caller() - set the method name to be included in an SQL comment.
- Other options
- option() - manually set an option in the $options array to be passed to IDatabase::select().
- options() - manually set multiple options in the $options array to be passed to IDatabase::select().
- straightJoinOption() - enable the STRAIGHT_JOIN query option.
- bigResult() - enable SQL_BIG_RESULT.
- bufferResult() - enable SQL_BUFFER_RESULT
- smallResult() - enable SQL_SMALL_RESULT
- calcFoundRows() - SQL_CALC_FOUND_ROWS
Run, fetch and count methods
edit- fetchResultSet() - run the constructed SELECT query and return all results. Returns instance of IResultWrapper .
- fetchField() - run the constructed SELECT query, and return a single field extracted from the first result row. This may only be called when only one field has been added to the builder.
- fetchFieldValues() - run the constructed SELECT query, and extract a single field from each result row, returning an array containing all the values. This may only be called when only one field has been added to the builder.
- fetchRow() - run the constructed SELECT query, and return the first result row (stdClass). If there were no results, return false.
- fetchRowCount()
- estimateRowCount() - estimate the number of rows in dataset that would be returned by a SELECT query, using EXPLAIN SELECT. The estimate is provided using index cardinality statistics, and is notoriously inaccurate, especially when large numbers of rows have recently been added or deleted.
- lockForUpdate() - run the SELECT query with the FOR UPDATE option. The field list is ignored.
- buildGroupConcatField() - combine a field for several rows into a single string. NULL values will not appear in the output, duplicated values will appear.
Other
edit- getSQL() - get the SQL query string which would be used by fetchResultSet().
- getQueryInfo() - get an associative array describing the query in terms of its raw parameters to Database::select(). This can be used to interface with legacy code.
Examples
edit$dbProvider = MediaWikiServices::getInstance()->getConnectionProvider();
$dbr = $dbProvider->getReplicaDatabase();
$res = $dbr->newSelectQueryBuilder()
->fields( [ 'cat_title', 'cat_pages' ] )
->table( 'category' )
->where( $dbr->expr( 'cat_pages', '>', 0 ) )
->orderBy( 'cat_title', SelectQueryBuilder::SORT_ASC )
->caller( __METHOD__ )
->fetchResultSet();
See Manual:Database access for further examples and guidance.
Extended by
edit- PageSelectQueryBuilder
- FileSelectQueryBuilder (since MW 1.41)
- LoggingSelectQueryBuilder