Performs a database query, using current database connection.
Description
More information can be found on the documentation page.
Parameters
$querystringrequired- Database query.
Source
public function query( $query ) { if ( ! $this->ready ) { $this->check_current_query = true; return false; } /** * Filters the database query. * * Some queries are made before the plugins have been loaded, * and thus cannot be filtered with this method. * * @since 2.1.0 * * @param string $query Database query. */ $query = apply_filters( 'query', $query ); if ( ! $query ) { $this->insert_id = 0; return false; } $this->flush(); // Log how the function was called. $this->func_call = "\$db->query(\"$query\")"; // If we're writing to the database, make sure the query will write safely. if ( $this->check_current_query && ! $this->check_ascii( $query ) ) { $stripped_query = $this->strip_invalid_text_from_query( $query ); /* * strip_invalid_text_from_query() can perform queries, so we need * to flush again, just to make sure everything is clear. */ $this->flush(); if ( $stripped_query !== $query ) { $this->insert_id = 0; $this->last_query = $query; wp_load_translations_early(); $this->last_error = __( 'WordPress database error: Could not perform query because it contains invalid data.' ); return false; } } $this->check_current_query = true; // Keep track of the last query for debug. $this->last_query = $query; $this->_do_query( $query ); // Database server has gone away, try to reconnect. $mysql_errno = 0; if ( $this->dbh instanceof mysqli ) { $mysql_errno = mysqli_errno( $this->dbh ); } else { /* * $dbh is defined, but isn't a real connection. * Something has gone horribly wrong, let's try a reconnect. */ $mysql_errno = 2006; } if ( empty( $this->dbh ) || 2006 === $mysql_errno ) { if ( $this->check_connection() ) { $this->_do_query( $query ); } else { $this->insert_id = 0; return false; } } // If there is an error then take note of it. if ( $this->dbh instanceof mysqli ) { $this->last_error = mysqli_error( $this->dbh ); } else { $this->last_error = __( 'Unable to retrieve the error message from MySQL' ); } if ( $this->last_error ) { // Clear insert_id on a subsequent failed insert. if ( $this->insert_id && preg_match( '/^\s*(insert|replace)\s/i', $query ) ) { $this->insert_id = 0; } $this->print_error(); return false; } if ( preg_match( '/^\s*(create|alter|truncate|drop)\s/i', $query ) ) { $return_val = $this->result; } elseif ( preg_match( '/^\s*(insert|delete|update|replace)\s/i', $query ) ) { $this->rows_affected = mysqli_affected_rows( $this->dbh ); // Take note of the insert_id. if ( preg_match( '/^\s*(insert|replace)\s/i', $query ) ) { $this->insert_id = mysqli_insert_id( $this->dbh ); } // Return number of rows affected. $return_val = $this->rows_affected; } else { $num_rows = 0; if ( $this->result instanceof mysqli_result ) { while ( $row = mysqli_fetch_object( $this->result ) ) { $this->last_result[ $num_rows ] = $row; ++$num_rows; } } // Log and return the number of rows selected. $this->num_rows = $num_rows; $return_val = $num_rows; } return $return_val; } Hooks
- apply_filters( ‘query’,
string $query ) Filters the database query.
Changelog
| Version | Description |
|---|---|
| 0.71 | Introduced. |
A simple query example using prepared statements
Be aware that because of the
preg_match( '/^\s*(insert|delete|update|replace)\s/i', $query )check inside this function, you may be surprised to not receive the expected$wpdb->rows_affected(and will miss the$wpdb->insert_idtoo) if you have anything except whitespace characters before the UPDATE/INSERT/etc. statement, e.g.:This will not work as expected – it will update your records but won’t return any value.