Question

I have two tables left joined. The query is grouped by the left table’s ID column. The right table has a date column called close_date. The problem is, if there are any right table records that have not been closed (thus having a close_date of 0000-00-00), then I do not want any of the left table records to be shown, and if there are NO right table records with a close_date of 0000-00-00, I would like only the right table record with the MAX close date to be returned.

So for simplicity sake, let’s say the tables look like this:

Table1
id
1
2

Table2
table1_id | close_date
1         | 0000-00-00
1         | 2010-01-01
2         | 2010-01-01
2         | 2010-01-02

I would like the query to only return this:

Table1.id | Table2.close_date
2         | 2010-01-02

I tried to come up with an answer using aliased CASES and aggregate functions, but I could not search by the result, and I was attempting not to make a 3 mile long query to solve the problem. I looked through a few of the related posts on here, but none seem to meet the criteria of this particular case.

Answer 1

Use:

SELECT t1.id,
       MAX(t2.close_date)
  FROM TABLE1 t1
  JOIN TABLE2 t2 ON t2.table1_id = t1.id
 WHERE NOT EXISTS(SELECT NULL
                    FROM TABLE2 t
                   WHERE t.table1_id = t1.id
                     AND t.closed_date = '0000-00-00')

The ‘0000-00-00’ should be implicitly converted by MySQL to a DATETIME. If not, cast the value to DATETIME.