t-sql NOT IN with multiple columns

Question

I have a Microsoft SQL database, where i am trying to insert some data. I have a unique key on 4 columns and i want to insert data from multiple tables into this table while checking the data to make sure it will not violate the uniqueness of the key. If i was doing this on a single column, i would do a NOT IN, like so..

INSERT TABLE_A (FLD_1)
    SELECT FLD_1
        FROM TBL_B
        INNER JOIN TBL_C
            ON TBL_B.FLD_1 = TBL_C.FLD_1
    WHERE TBL_B.FLD_1 NOT IN
        (
        SELECT TBL_A.FLD_1 FROM TBL_A
        )

Any thoughts?

Answer 1

Use NOT EXISTS instead since you have to deal with multiple columns.

http://www.techonthenet.com/sql/exists.php

EDIT:

Untested, but roughly it will be this:

SELECT FLD_1
FROM TBL_B
INNER JOIN TBL_C  ON TBL_B.FLD_1 = TBL_C.FLD_1
WHERE NOT EXISTS 
    (
    SELECT TBL_A.FLD_1 FROM TBL_A INNER JOIN TBL_B ON TBL_B.FLD1 = TBL_A.FLD1
    )

For a multi-column check it would be roughly this:

SELECT FLD_1, FLD_2, FLD_3, FLD_4)
FROM TBL_B
INNER JOIN TBL_C  ON TBL_B.FLD_1 = TBL_C.FLD_1
WHERE NOT EXISTS 
    (
    SELECT TBL_A.FLD_1, TBL_A.FLD_2, TBL_A.FLD_3, TBL_A.FLD_4 
    FROM TBL_A 
    INNER JOIN TBL_B ON TBL_B.FLD1 = TBL_A.FLD1 AND 
                        TBL_B.FLD2 = TBL_A.FLD2 AND 
                        TBL_B.FLD3 = TBL_A.FLD3 AND 
                        TBL_B.FLD4 = TBL_A.FLD4 
    )