wpdb::query( string $query ): int|bool

Performs a database query, using current database connection.


Description

More information can be found on the documentation page.


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Parameters

$query string Required
Database query.

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Return

int|bool Boolean true for CREATE, ALTER, TRUNCATE and DROP queries. Number of rows affected/selected for all other queries. Boolean false on error.


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Source

File: wp-includes/class-wpdb.php. View all references

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 ( ! empty( $this->dbh ) ) {
		if ( $this->use_mysqli ) {
			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;
			}
		} else {
			if ( is_resource( $this->dbh ) ) {
				$mysql_errno = mysql_errno( $this->dbh );
			} else {
				$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->use_mysqli ) {
		if ( $this->dbh instanceof mysqli ) {
			$this->last_error = mysqli_error( $this->dbh );
		} else {
			$this->last_error = __( 'Unable to retrieve the error message from MySQL' );
		}
	} else {
		if ( is_resource( $this->dbh ) ) {
			$this->last_error = mysql_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 ) ) {
		if ( $this->use_mysqli ) {
			$this->rows_affected = mysqli_affected_rows( $this->dbh );
		} else {
			$this->rows_affected = mysql_affected_rows( $this->dbh );
		}
		// Take note of the insert_id.
		if ( preg_match( '/^\s*(insert|replace)\s/i', $query ) ) {
			if ( $this->use_mysqli ) {
				$this->insert_id = mysqli_insert_id( $this->dbh );
			} else {
				$this->insert_id = mysql_insert_id( $this->dbh );
			}
		}
		// Return number of rows affected.
		$return_val = $this->rows_affected;
	} else {
		$num_rows = 0;
		if ( $this->use_mysqli && $this->result instanceof mysqli_result ) {
			while ( $row = mysqli_fetch_object( $this->result ) ) {
				$this->last_result[ $num_rows ] = $row;
				$num_rows++;
			}
		} elseif ( is_resource( $this->result ) ) {
			while ( $row = mysql_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;
}

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Hooks



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Changelog

Changelog
Version Description
0.71 Introduced.

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User Contributed Notes

  1. Skip to note 2 content
    Contributed by nobug

    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.:

    $rows_affected = $wpdb->query(
    	"# this comment breaks the $return_val
    	UPDATE wp_postmeta SET meta_value = 'baz'
    	WHERE meta_key = 'foo' AND meta_value = 'bar'"
    );
    echo $rows_affected; // will output 0 (actually $num_rows)

    This will not work as expected – it will update your records but won’t return any value.

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