Question

Can I refactor the below SQL CASE statements into single for each case ?

SELECT 
  CASE RDV.DOMAIN_CODE  WHEN 'L' THEN CN.FAMILY_NAME  ELSE NULL END AS [LEGAL_FAMILY_NAME],
  CASE RDV.DOMAIN_CODE  WHEN 'L' THEN CN.GIVEN_NAME  ELSE NULL END AS [LEGAL_GIVEN_NAME],
  CASE RDV.DOMAIN_CODE  WHEN 'L' THEN CN.MIDDLE_NAMES  ELSE NULL END AS [LEGAL_MIDDLE_NAMES],
  CASE RDV.DOMAIN_CODE  WHEN 'L' THEN CN.NAME_TITLE  ELSE NULL END AS [LEGAL_NAME_TITLE],

  CASE RDV.DOMAIN_CODE  WHEN 'P' THEN CN.FAMILY_NAME  ELSE NULL END AS [PREFERRED_FAMILY_NAME],
  CASE RDV.DOMAIN_CODE  WHEN 'P' THEN CN.GIVEN_NAME  ELSE NULL END AS [PREFERRED_GIVEN_NAME],
  CASE RDV.DOMAIN_CODE  WHEN 'P' THEN CN.MIDDLE_NAMES  ELSE NULL END AS [PREFERRED_MIDDLE_NAMES],
  CASE RDV.DOMAIN_CODE  WHEN 'P' THEN CN.NAME_TITLE  ELSE NULL END AS [PREFERRED_NAME_TITLE]

FROM dbo.CLIENT_NAME CN
JOIN dbo.REFERENCE_DOMAIN_VALUE RDV 
ON CN.NAME_TYPE_CODE = RDV.DOMAIN_CODE AND RDV.REFERENCE_DOMAIN_ID = '7966'

Answer 1

No, you will require 8 separate statements as case and other such variants can only be used in a select to modify the results of a single column, not a series of columns.