Question

I have a complicated query I’ve been working on, and I recently changed one of the columns so that there will be multiple entries that reference the same foreign key.

Is there a simple way to make it so that if there are 1 or more entries with the same foreign key that a value of “true” (or some other value) is returned rather than n seperate rows?

eg.

I want this:

id |  Date
1  |  true
2  |  NULL

instead of this (what is happening now):

id |  Date
1  |  feb 4
1  |  feb 5
1  |  feb 6
2  |  NULL
2  |  feb 5

if there are no values I just want a null for the date

EDIT
I forgot about the case where you have both values and nulls for the same primary key (id# 2). In this case I need to be able to return Null. If there are any nulls then it should return a null.
EDIT

I’ve tried playing around with a group by function but can’t get anything close to what I’m trying to accomplish

This is a simplified version of my query as it is already, don’t want to confuse the issue with the extra columns.

SELECT distinct job, DATE_FORMAT( scan_date, '%M %e, %Y, %l:%i%p' ) AS Scanning
FROM Scan, job
WHERE Scan.job_job = job

Answer 1

Check if any scan record exists rather than joining to the Scan table directly:

SELECT distinct job, exists(select 1 from Scan where Scan.job_job = job) AS Scanning
FROM job;

This will return 1 if a Scan record exists, 0 if not. If you really want to use “true” and NULL, you can wrap the exists in IF().