Drop that unknown NOT NULL constraint - Part 2

Recently I got word from someone at a Database Forum pointing that it would be easier to join a couple tables to get the name of the constraint we want to drop.

The code is this:

SELECT c.constraint_name
FROM user_tab_columns t, user_cons_columns c
WHERE t.table_name = my_table
AND t.table_name = c.table_name
AND t.column_name = my_column
AND t.nullable = 'N';

That's it, we got now the constraint name and can drop it easely.

That would shorten the script a lot, tho the performance will probably depend on various details as the number of rows per table and the position of the value we look up.

So, the new script would look as follows:

DECLARE
constname user_cons_columns.constraint_name%TYPE;
BEGIN
SELECT c.constraint_name INTO constname
FROM user_tab_columns t, user_cons_columns c
WHERE t.table_name = my_table
AND t.table_name = c.table_name
AND t.column_name = my_column
AND t.nullable = 'N';

EXECUTE IMMEDIATE 'ALTER TABLE my_table DROP CONSTRAINT ' || 'constname';
dbms_output.put_line('Constraint '|| constname || ' dropped successfuly!');
COMMIT;
END;

Nevertheless and despite the obvious change in the size and performance of this script, during the test, I found something interesting: it fails if the constraint is disabled, due to the fact that user_tab_columns.nullable contains the current value of the system itself and not the one from the constraint.