Question

I’m trying to write a query that combines finding a particular record (identified by primary key) having its status column set to CONFIRMED but can also find whether that primary key exists in the table at all. This is what I tried:

SELECT 
count(`p2`.`id`) AS `confirmed`,
count(`p1`.`id`) AS `exists`
FROM `foos` `p2`, `foos` p1`
WHERE
`p2`.`id` = 28 AND 
`p2`.`status` = 'CONFIRMED' AND
`p1`.`id` = 28

So again, I’m trying to find if there exists a foo with id = 28 and status = 'CONFIRMED' but I also want to know whether the id doesn’t exist or whether it does exist but the status isn’t confirmed. MySQL says there’s a problem with this query near

`p2`.`id` = 28 AND 
`p2`.`status` = 'CONFIRMED'

Is this query possible at all?

Answer 1

I would solve it like this:

SELECT COUNT(a1.id) AS EXISTS, 
       IF(status = 'CONFIRMED', 1, 0) AS confirmed 
FROM   foo f1 
       LEFT JOIN foo f2 
         ON f1.id = f2.id 
WHERE  f1.id = 28