Using Case in a SQL Query

Using Case in Update Statement
UPDATE dbo.Customer SET stateDescription = CASE WHEN statecode = 'MA' THEN 'Massachusetts' WHEN statecode = 'VA' THEN 'Virginia' WHEN statecode = 'PA' THEN 'Pennsylvania' ELSE NULL END
 
Using Case in Select Statement
SELECT COUNT(*) AS TotalCustomers, 
SUM(CASE WHEN statecode = 'MA' THEN 1 ELSE NULL END) AS TotalMassCustomers, 
AVG(CASE WHEN statecode = 'MA' THEN totalsales ELSE NULL END) AS TotalMassSales 
FROM dbo.Customer 

Using Case in Stored Procedure

CREATE PROCEDURE dbo.getCustomerData @sortby VARCHAR(9), @sortdirection CHAR(4) AS
SET nocount ON

SELECT customerid, firstname, lastname, statecode, statedescription, totalsales FROM dbo.Customer ORDER BY  CASE @sortdirection
     WHEN 'asc' THEN
      CASE @sortby 
       WHEN 'firstname' THEN firstname 
       WHEN 'lastname' THEN lastname 
       END
END 
ASC, CASE @sortdirection
      WHEN 'desc' THEN
       CASE @sortby 
       WHEN 'firstname' THEN firstname 
       WHEN 'lastname' THEN lastname 
       END
END
DESC GO EXEC dbo.getCustomerData 'lastname', 'desc' 

Selecting Record to using cursor in stored procedure

Following is an example using cursor to fetch record from table and performing action on each row using while loop, also used try catch in this stored procedure

ALTER PROCEDURE [dbo].[Test_Procedure_By_Khalid]

(

      -- Add the parameters for the stored procedure here

      @TableName nvarchar(255),

      @AreaName varchar(50),

      @SysDate DateTime,

      @ReturnCode INT   OUTPUT

)

AS

     

      DECLARE @GraphID NVARCHAR(50)

      DECLARE @PERIOD INT

      DECLARE @MODELKEY NVARCHAR(50)

      DECLARE @ORIGNALDATE NVARCHAR(50)

      DECLARE @DATE INT

      DECLARE @QTY INT

      DECLARE @TOTALQTY INT

      DECLARE @MODELKEYTYPE INT

      DECLARE @SCREENID NVARCHAR(50)

      DECLARE @RetailModelClassificationName NVARCHAR(50)

      DECLARE @SELECTEDAREA varchar(50)

      DECLARE @INF_Cursor INT

      DECLARE @THEMONTH NVARCHAR(6)

      DECLARE @LASTMONTH NVARCHAR(6)

      DECLARE @LASTYEARMONTH NVARCHAR(6)

      --Cursor Definition

      DECLARE     @Cur_TableParm    CURSOR

     

BEGIN TRY

      ----------------------------

      -- Start Transaction --

      ----------------------------

      BEGIN TRANSACTION

-- Set Cursor to select data from Table CPT_TableParm

      SET @Cur_TableParm = CURSOR FAST_FORWARD FOR

SELECT GraphID,ModelKey,AreaName,ModelClassificationName,ScreenID FROM CPT_TableParm

      WHERE TableName = @TableName

      AND ActFcType = 1

     

      -- Executing Cursor to select data from Table CPT_TableParm

      OPEN  @Cur_TableParm

      FETCH NEXT FROM @Cur_TableParm  INTO

             @GraphID, @MODELKEY,@SELECTEDAREA,

 @RetailModelClassificationName,@SCREENID

     

      -- Looping through cursor result   

      WHILE  @@FETCH_STATUS = 0

        BEGIN

           

Print  @SELECTEDAREA+','+cast(@PERIOD as varchar)+'~'+@MODELKEY+'~'+@ORIGNALDATE+'~'+cast(@DATE as varchar)+'~'+cast(@QTY as varchar)+'~'+

                                          cast(@TOTALQTY as varchar)+'~'+@GraphID+'~''3''~'+@SCREENID

                              SET @ReturnCode = 2

        FETCH NEXT FROM @Cur_TableParm  INTO

                                    @GraphID, @MODELKEY,@SELECTEDAREA,

@RetailModelClassificationName,@SCREENID

       END

      -- Closing @Cur_TableParm to select data from CPT_TableParm

      CLOSE       @Cur_TableParm

      DEALLOCATE  @Cur_TableParm

END TRY

BEGIN CATCH

-- Rollback Transaction --

      ROLLBACK TRANSACTION

      -- Reset Cursor State

      BEGIN

            SET @INF_Cursor = CURSOR_STATUS('global','@Cur_TableParm')

            IF @INF_Cursor = -1

            BEGIN

                  DEALLOCATE  @Cur_TableParm    -- Delete Cursor

            END

            ELSE IF @INF_Cursor <> -3

                  BEGIN

                        CLOSE       @Cur_TableParm    -- Close Cursor

                        DEALLOCATE  @Cur_TableParm    -- Delete Cursor

                  END

            PRINT       ERROR_MESSAGE()

      END

      RETURN 999

END CATCH