ORA-55747
The SET clause of a reservable update statement requires the amount to be added or subtracted from the same reservable column, "string".
Cause
An amount is being not added or subtracted from the same reservable column.
Action
Change the update statement to add or subtract from the same reservable column. The set clause should be of the form reservable_col1 = reservable_col1 + (expression) or reservable_col1 = reservable_col1 - (expression)." where the expression in parenthesis evaluates to the amount to be added or subtracted from the same reservable column, reservable_col1.