Question

I need to join tableA, tableB, and tableC, but it’s possible that tableB won’t have a corresponding row. Posted below is how I am currently doing the query. The problem with it is that if tableB doesn’t have a correspoinding row, it won’t return a result. My sql skills are very rusty so I appreciate your help. Thanks.

SELECT [column names]
FROM tableA AS a, tableB AS b, tableC as c
WHERE b.blah = a.blah
AND c.foo = a.foo
AND [more where conditions]

Answer 1

Use a LEFT JOIN.

SELECT [column names]
FROM 
    tableA AS a 
    LEFT JOIN tableB AS b ON b.blah = a.blah
    JOIN tableC as c ON c.foo = a.foo