How To Use CASE Expression


  • 6 Mar, 2012

    There are 2 ways to use the CASE expression. The first way is to return one of the predefined values based on the comparison of a given value to a list of target values. The second way is to return one of the predefined values based on a list of conditions. Here is the syntax of both types of CASE expressions:CASE value WHEN target_value THEN result WHEN target_value THEN result WHEN target_value THEN result ... ELSE result END CASE WHEN condition THEN result WHEN condition THEN result WHEN condition THEN result ... ELSE result END The tutorial exercise below gives two good examples:SELECT CASE 'Sun' WHEN 'Mon' THEN 'Open' WHEN "Fri" THEN "Open" ELSE 'Closed' END FROM DUAL; ClosedSELECT CASE WHEN HOUR(CURRENT_TIME())<9 THEN 'Closed' WHEN HOUR(CURRENT_TIME())>17 THEN 'Closed' ELSE 'Open' END FROM DUAL; Closed

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