Issue
I would like to user condition like this:
IF (EXISTS A) AND (NOT EXISTS B) THEN...
A and B conditions are like this:
SELECT * FROM table WHERE flag=1
E.g.:
IF EXISTS (SELECT * FROM table WHERE flag=1)
AND NOT EXISTS (SELECT * FROM table WHERE flag=2)
THEN
INSERT INTO table (id, name, flag) VALUES (0, 'name', 2);
END IF;
In this case, the "(EXISTS A) and (NOT EXISTS B)" condition is true.
but the query don’t enter into ‘THEN’.
Could i know what’s wrong?
Solution
The IF you are using is not available outside of a stored procedure or maybe trigger. Instead, you should use an INSERT INTO ... SELECT:
INSERT INTO yourTable (id, name, flag)
SELECT 0, 'name', 2
WHERE EXISTS (SELECT 1 FROM yourTable WHERE flag = 1) AND
NOT EXISTS (SELECT 1 FROM yourTable WHERE flag = 2);
Answered By – Tim Biegeleisen
Answer Checked By – Robin (BugsFixing Admin)