SQL: INSERT INTO...VALUES..SELECT

Question

How do I write INSERT statement if I get the values of colA from TableX, colB from TableY and colC from TableZ?

For example:

INSERT INTO TableA (colA, colB, colC) VALUES (?,?,?)

Any ideas if it is possible?

Answer 1

INSERT INTO TableA(colA, colB, colC)
  SELECT TableX.valA, TableY.valB, TableZ.valC
    FROM TableX
   INNER JOIN TableY ON :......
   INNER JOIN TableZ ON ........

Of course, TableX, TableY and TAbleZ might also be related in some other way (not INNER JOIN).

If you cannot find any relation between the tables AT ALL, you could also do three separate

SELECT @value1 = valA FROM TableX WHERE ......
SELECT @value2 = valB FROM TableY WHERE ......
SELECT @value3 = valC FROM TableZ WHERE ......

and then an insert like this:

INSERT INTO TableA(colA, colB, colC)
             VALUES(@value1, @value2, @value3)

That's the ultimate last resort, you can can't express everything in a single SELECT statement.

Marc

Answer 2

In response to marc_s's answer, you can query from unrelated tables in a since select like:

INSERT INTO TableA
    (colA, colB, colC)
SELECT
    (SELECT valA FROM TableX WHERE ...),
    (SELECT valB FROM TableY WHERE ...),
    (SELECT valC FROM TableZ WHERE ...)