Using CASE to UPDATE a column

• sqlrumble

  Default port

  Points: 1458

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  November 23, 2004 at 5:24 am

  #60609

  Hello,

  I am trying to create a CASE statment which will update a column depending on the outcome of a select statement.

  The following stored procedure works without using CASE:

  UPDATE <TABLE2>

  SET <COLUMN_X> = 'N' 

  FROM <TABLE1> RIGHT OUTER JOIN

                        <TABLE2> ON <TABLE1.COLUMNID> = <TABLE2.COLUMNID>

  WHERE     (<TABLE1.COLUMNID> IS NULL)

  I need to set up a stored procedure which will set 'N' if in the where statement is NULL and set 'Y' if the where statement is NOT NULL.

   

  Hope this makes sense.

   

  Thanks in advance

   

   

   

   

   

• Johan Bijnens

  SSC Guru

  Points: 135376

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  November 23, 2004 at 6:09 am

  #531205

  Is this what you're looking for ?

  I prefer using Left outerjoins because I find them to be more readable.

  I also like using objectaliases because I find them to make the query more readable.

  UPDATE <TABLE2>

  SET <COLUMN_X> = case when <T1.COLUMNID> IS NULL then 'N' 

                                      else 'Y'

                                      end

  FROM <TABLE2>  T2

  LEFT OUTER JOIN <TABLE1> T1

  ON <T2.COLUMNID> = <T1.COLUMNID>

  -- WHERE     (<TABLE1.COLUMNID> IS NULL)

  Test it for your means

   

  Johan
  
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