scalar subquery in if statement Condition in PL/SQL

Question

I have an If Statement block similar to the below which is failing with the error - PLS-00103: Encountered the symbol \"SELECT\" when expecting one of the following....

Answer 1

I don't believe subqueries are supported in IF conditions... PL/SQL will be expecting the SELECT to give it a set of records, not a single value to be used in a expression/statement.

Answer 2

Have you called DBMS_OUTPUT.ENABLE

Quick example

BEGIN
DBMS_OUTPUT.DISABLE;
DBMS_OUTPUT.PUT_LINE('Disabled');
DBMS_OUTPUT.ENABLE;
DBMS_OUTPUT.PUT_LINE('Enabled');
END;

Answer 3

No, you can't use a SELECT in the way you want.

In your example using CASE, you are not using a CASE "statement" -- you are using a CASE expression, which happens to be embedded within a SQL statement. You can use a subquery in that case because it's within the context of a SQL statement, not a procedural statement. You wouldn't be able to use a subquery like this in a procedural CASE statement.