Performs a database query, using current database connection.
Description
More information can be found on the documentation page.
Parameters
$query
stringrequired- 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_id
too) 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.