Selecting boolean in MySQL based on contents of another table

Question

I have the following tables:

Name: Posts

Id Creator Title Body Tags Time
1  1       Test  Test Test 123456789

and

Name: Action         


        

Answer 1

SELECT Posts.*, IF(Action.Id IS NULL,0,1) as Deleted 
FROM Posts 
LEFT JOIN Action 
ON Action.Target = Posts.Id and Type='delete'

If you don't care about perfomance

SELECT Posts.*,
       exists
  (SELECT 1
   FROM Action
   WHERE Target = Posts.Id
     AND TYPE='delete') AS Deleted
FROM Posts