Question

I have two tables

Table A
-------
ID
ProductName

Table B
-------
ID
ProductID
Size

I want to join these two tables

SELECT * FROM
   (SELECT * FROM A)
   LEFT JOIN
   (SELECT * FROM B)
ON A.ID = B.ProductID

This is easy, I will get all rows from A multiplied by rows matched in B, and NULL fields if there is no match.

But here comes the tricky question, how can I get all rows from A with NULL fields for table B, even if there is a match, so I get an extra line with NULL values plus all the matches?

Answer 1

Instead of using UNION ALL in a subquery as suggested by others, you could also (and I would) use UNION ALL at the outer level, which keeps the query simpler:

SELECT A.ID, A.ProductName, B.ID, B.Size
FROM A
INNER JOIN B
ON B.ProductID = A.ID
UNION ALL
SELECT A.ID, A.ProductName, NULL, NULL
FROM A