SQL UPDATE statement with WHERE EXISTS

Question

Im trying to write a query that updates a date only if the group im updating has a LINE_CD of 50. Would i do it like this?

UPDATE EMPLOYER_ADDL  
SET EMPLOYER_A         


        

Answer 1

I believe exists requires a wildcard:

UPDATE EMPLOYER_ADDL  
SET EMPLOYER_ADDL.GTL_UW_APPRV_DT = EMPLOYER_ADDL.DNTL_UW_APPRV_DT 
WHERE EXISTS
    ( 
      SELECT *
      FROM EMP_PLAN_LINE_INFO
      Where EMP_PLAN_LINE_INFO.GR_NBR = EMPLOYER_ADDL.GR_NBR and
       EMP_PLAN_LINE_INFO.LINE_CD = 50
     )

I prefer using IN though. Some argue that it can be slower, but I have found the SQL optimizer in 2005 and higher make IN work the same as EXISTS if the field is a non-null field.

UPDATE EMPLOYER_ADDL  
SET EMPLOYER_ADDL.GTL_UW_APPRV_DT = EMPLOYER_ADDL.DNTL_UW_APPRV_DT 
WHERE EMPLOYER_ADDL.GR_NBR IN
    ( 
      SELECT EMP_PLAN_LINE_INFO.GR_NBR
      FROM EMP_PLAN_LINE_INFO
      Where EMP_PLAN_LINE_INFO.LINE_CD = 50
     )