SELECT column1, column2,

  CASE

    WHEN condition1 THEN value1

    WHEN condition2 THEN value2

    ELSE value3

  END AS result_column

FROM your_table;

INSERT INTO HumanResources.departmentcopy(DepartmentID, GroupName, Name, temp)

SELECT  DepartmentID,

        GroupName,

        Name,

        CASE WHEN DepartmentID = 1 AND Name = 'Engineering and Research'

        THEN 'sucessful' ELSE 'unsucessful' END

FROM HumanResources.department

--CREATE SOME SAMPLE DATA

​

CREATE TABLE Casedata

  (

     NAME VARCHAR(10)

  );

​

INSERT INTO Casedata VALUES ('Test 1');

INSERT INTO Casedata VALUES ('Test 2');

INSERT INTO Casedata VALUES ('None');

​

-- CASE WHEN IN SQL

SELECT NAME,

       CASE

         WHEN NAME = 'Test 1' THEN 'The value is 1'

         WHEN NAME = 'Test 2' THEN 'The value is 2'

         ELSE 'Sorry no Match'

       END

FROM   Casedata 

CASE

    WHEN SUBSTRING(applications.pinfl, 1,1) IN ('3','5','7') THEN 'Erkak'

    WHEN SUBSTRING(applications.pinfl, 1,1) IN ('2','4','6') THEN 'Ayol'

    ELSE 'Topilmadi'

END as gender

-- Case Eg.) to retrive the MAX value of a Field 

-- if there are entries for the Field in table MAX value will be returned 

-- But if there is no entries at all for the Field in tabel MAX will return

-- Null as the output. But Using Case When we can check it out return zero 

-- or any other value if there is no enties for the Field in table..

SELECT 

CASE   -- Like Switch Case

    WHEN -- First When condition 

        (MAX(BILLID) IS NULL) -- Condition 

    THEN 1   -- output   (We can also add more When conditions like Above)

ELSE -- When WHEN Condition not Satisfied Below will be Executed. 

        (MAX(BILLID)) -- output

END 

as MAXBILLID   from  DUAL;

-- Final Output

-- If there is no entry in the Field for the table

-- BILLID

--  1

-- If there are entries MAX of that Field value from the table

-- BILLID

-- 10

SELECT column_name,

    CASE 

      WHEN boolean_condition THEN 'Result_1'

      WHEN boolean_condition THEN 'Result_2'

      ELSE 'Result_3'

    END AS result_column_name

 FROM table_name_1  

 LEFT JOIN table_name_2 ON

    CASE 

      WHEN boolean_condition THEN 'Boolean_Result_1'

      WHEN boolean_condition THEN 'Boolean_Result_2'

      ELSE 'Boolean_Result_3'

    END;