Using VARRAY to Remove Values in PL/SQL DROP Command

Data and Databases
1

I am attempting to initialize an array using a select query, and then eliminate values obtained from that query.

DECLARE 
TYPE array_type IS VARRAY(20) OF VARCHAR2(30);
constraintList array_type := array_type();
BEGIN

SELECT COUNT(1) INTO v_exists FROM user_constraints 
WHERE constraint_name != 'specific_value' AND table_name = 'specific_value';

FOR i IN NVL(constraintList.FIRST, 0) .. NVL(constraintList.LAST, -1) LOOP
  #set($currentName = constraintList(i))
  EXECUTE IMMEDIATE 'ALTER TABLE ${specific_value} DROP CONSTRAINT ${currentName} DROP INDEX';
END LOOP;

END;

However, I encounter an exception. Can anyone guide me on how to resolve this?

2

It seems like the issue may be related to how the VARRAY is being populated and iterated. In your code, the constraintList is not populated with values from the query result. To resolve this, you should first populate the VARRAY constraintList with the constraint names retrieved from the SELECT statement. You can use a BULK COLLECT into a collection type such as VARRAY or a PL/SQL table. Additionally, ensure each constraint name retrieved is inserted into constraintList before attempting to loop through and drop constraints. This should prevent the exception you are encountering.

3

you might also wnat to check if constraints are actually existing before executing the drop statements. add a check for each constraint to see if it’s truly present in the constraintList to prevent errors, just so you don’t try to drop something that isn’t there. cheers!

4

hey, your approach is interesting! have you considered using a subtype instead of a varray for more flexibility? I’m curious if integrating a nested table instead may help with performance, especially since they offer dynamic sizing. how’s your current performance holding up?

5

It appears like you need to ensure that your dynamic SQL is correctly formed and executed in the loop. When forming a dynamic SQL string with PL/SQL variables, it’s crucial to use bind variables to avoid errors related to data conversion and SQL injection risks. Since you’ve already captured the constraint names, confirm that your ALTER TABLE command uses appropriate concatenation or passes variables securely. Also, make sure you test the SQL command manually outside of PL/SQL to verify its correctness before looping.