title: t-sql NOT IN with multiple columns
body: <p>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..</p>
  
  <pre><code>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
          )
  </code></pre>
  
  <p>Any thoughts?</p>