Question

I’m checking if a column value is blank because I need to add 1 to it. This is actually a follow up of my question here

My Previous Question

I’m doing

INSERT INTO posts (post_user_id, gen_id)  SELECT 1, IFNULL((MAX(gen_id)+1 FROM
posts),0);

What’s wrong here?

I keep getting some kind of error.

Answer 1

try substituting it with COALESCE

INSERT INTO posts (post_user_id, gen_id) 
SELECT 1, COALESCE((MAX(gen_id)+1) ,0) 
FROM posts

• See SQLFiddle Demo

or IFNULL

INSERT INTO posts (post_user_id, gen_id) 
SELECT 1, IFNULL((MAX(gen_id)+1) ,0) 
FROM posts

• See SQLFiddle Demo