WHERE Clause only IF NOT NULL

Question

I need help with my SELECT.

I got a field that can be NULL and in it there is stored a foreign-key.

SELECT * FROM beerImage WHERE beerBRewID = brewID AND beerBrandID = beerID <--- this can be NULL

So if it's NULL nothing happens.

How can I check if beerID is NOT NULL so I can use "beerBrandID = beerID"?

Answer 1

You probably need something like this:

First example:

SELECT * FROM beerImage WHERE beerBRewID = brewID AND (beerID IS NULL OR beerBrandID = beerID)

Second Example:

SELECT * FROM beerImage WHERE beerBRewID = brewID AND beerID IS NOT NULL AND beerBrandID = beerID

The first example will allow you to show records which have beerID null along with the beers which beerBrandID is equal to beerID (both).

The second one will return exactly beers which correspond to beerBrandID (excluding NULL beerIDs).

Answer 2

How about using with CASE statement in where clause like

WHERE
CASE WHEN  beer.id IS NOT NULL 
    THEN beer.brand_id = 12345
    ELSE TRUE
END