WHERE with CASE and null checking
12,057
Solution 1
This should work:
SELECT *
FROM
docs
WHERE (date1 < '20120601')
OR (date2 IS NOT NULL AND date2 < '201205601')
OR (date2 IS NULL AND date3 IS NOT NULL AND date3 < '20120601')
Solution 2
where
date1 < '20120601'
and
coalesce(date2, date3, '20000101') < '20120601'
Author by
Robert Niestroj
I'am a Java (Wicket, Wildfly, Hibernate, JPA, Spring, Spring Data) and JavaScript (Vue, ES6, Quasar) Developer.
Updated on June 18, 2022Comments
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Robert Niestroj almost 2 years
i have a problem with a CASE statement in a WHERE clause. In my query i want to get rows which are before a date. The date is check on 3 columns.
date1
is NOT NULL so i dont need there a NULL check, but datesdate2
anddate3
can be NULL so i want to check for nulls and accordingly check the date condition. I tried two approaches but cant figure out how to do it right. Can you help?Query 1:
SELECT * FROM docs WHERE date1 < '20120601' AND CASE WHEN date2 IS NOT NULL AND date3 IS NOT NULL THEN date2 < '20120601' WHEN date2 IS NOT NULL AND date3 IS NULL THEN date2 < '20120601' WHEN date2 IS NULL AND date3 IS NOT NULL THEN date3 < '20120601' END
This gives and error in the first when:
Incorrect syntax near '<'.
I modified my query to this:
SELECT * FROM docs WHERE date1 < '20120601' AND CASE WHEN date2 IS NOT NULL AND date3 IS NOT NULL AND date2 < '20120601' THEN TRUE WHEN date2 IS NOT NULL AND date3 IS NULL AND date2 < '20120601' THEN TRUE WHEN date2 IS NULL AND date3 IS NOT NULL AND date3 < '20120601' THEN TRUE END
and got another error:
An expression of non-boolean type specified in a context where a condition is expected, near 'END'.