Trying to update the "size" column with the value of "file" column.
BEGIN set NEW.size=SUM(LENGTH(file)); END
UPDATE `table`.`library` SET `_by`='Danis555, Vovan244' WHERE `id`='20';
Operation failed: There was an error while applying the SQL script to the database.
ERROR 1111: 1111: Invalid use of group function SQL Statement: UPDATE
_by='Danis555, Vovan244' WHERE
LENGTHs do you expect to be returned for one column in one row that you need to