Question

Possible silly question, but got me stumped. Compare 2 tables and return only distinct columns.

        SELECT DISTINCT(DM.CLIENT_CODE) FROM DBO.DM_CLIENT DM
        LEFT JOIN DBO.STG_DM_CLIENT STG
        ON STG.CLIENT_CODE = DM.CLIENT_CODE

Aim of query is to return only new client_codes from DM table (or client_codes not listed in STG table).

I tought this would work, however does not.

can this query be then used in a case query to validate when new codes exists, then set resultset to ‘A’

       select  case 
            when (SELECT DBO.DM_CLIENT.Client_Code  
            FROM DBO.DM_CLIENT DM  
            LEFT JOIN DBO.STG_DM_CLIENT STG    
          ON STG.Client_Code= DM.Client_Code  
            WHERE STG.Client_Code IS NULL  
          GROUP BY  DM.Client_Code) then 'A'
       end

       from  DBO.DM_CLIENT.Client_Code, DBO.STG_DM_CLIENT.Client_Code

How can I make that statement to be a conditional statement?

Answer 1

Sounds like you want to return those from DM that don’t exist in STG.

 SELECT DM.Client_Code
 FROM DBO.DM_CLIENT As DM
 LEFT JOIN DBO.STG_DM_CLIENT As STG 
   ON STG.Client_Code= DM.Client_Code
 WHERE STG.Client_Code IS NULL
 GROUP BY  DM.Client_Code;