In order to have these functions available, you must compile PHP with fbsql support by using the --with-fbsql[=DIR] option. If you use this option without specifying the path to fbsql, PHP will search for the fbsql client libraries in the default installation location for the platform. Users who installed FrontBase in a non standard directory should always specify the path to fbsql: --with-fbsql=/path/to/fbsql . This will force PHP to use the client libraries installed by FrontBase, avoiding any conflicts.