Modify argument values

Do not modify a UDR argument unless it is an OUT parameter. The routine manager does not make routine-specific copies of the arguments that it passes to UDRs because it is more efficient not to do so. Keep in mind that values passed into a UDR are often used on other places in the SQL statement. If you modify a pass-by-reference value within the UDR, you also modify it for all other parts of the SQL statement (including other UDRs) that operate on the value after the UDR executes. When you modify a pass-by-reference argument within the UDR, you might create an order-dependent result of the SQL statement. That is, it now might make a difference when your UDR is run within the SQL statement.