SQLite question (Sorry if I choose the wrong topic category ) I am creating a trigger for my SQLite code, which it uses to update the field rental_cost (inside table Rental, default NULL) if someone UPDATE or INSERT the related table, the rental_cost is a REAL field that requires calculation and data from another table so I use JOIN to grip data from other tables, however, it shows the above error code when I tried to test it. Rental table structure ![image|549x160](upload://ba05X2OIOGgrfpZA7922lj186vk.png) The Trigger ``` CREATE TRIGGER updater AFTER UPDATE ON Rental FOR EACH ROW WHEN OLD.rental_cost = NULL AND NEW.date_back != NULL BEGIN SELECT price FROM Rental JOIN License USING ( license_id ) JOIN Title USING ( title ); UPDATE Rental SET rental_cost = 3 + price * 0.05 * (date_out) - (date_back) WHERE rental_cost = NULL; END; ``` Test code to update the table ``` UPDATE Rental SET date_back = '0000-00-11 11:11:11' WHERE gamer_id = '12' AND license_id = '71811'; ``` Expected outcome: the data_back update manually, and trigger detect the update, calculate and update the rental_cost automatically. Edited 1.0 : The SQLiteStudio empty field IS NOT NULL, when I use ` SELECT rental_cost FROM gameRental WHERE rental_cost IS NOT NULL the last field which is empty by default, show up in the query result. Vice versa, when IS NULL, the query result show nothing Edited 2.0 : This is weird. When I completely delete the table and recreate it, use SQL edit instead of the provided Triggers Function from the SQLITeStudio Tools bar, and type all the code myself, the trigger works.