Aside from what others have noted (that PHP doesn't currently support `sqlite3_create_window_function`), the [function documentation](https://sqlite.org/c3ref/create_function.html) also states (emphasis mine): > The sixth, seventh, eighth and ninth parameters (`xStep`, `xFinal`, `xValue` and `xInverse`) passed to `sqlite3_create_window_function` are pointers to **C-language callbacks** that implement the new function. I'm curious as to how you're expecting the PHP equivalent to work. What exactly are the parameters you're passing to `$db->createWindowFunction()`?