StoredProcedure:How to subtact previous value from recent value that value displayed in another column

Uh oh... looks like I owe you and Zoran an apology... I didn't understand the requirement correctly and didn't realize the rows were interdependent.

In that case you need to follow Zoran's example, because you do need to go through the table and find the MAX(empid).

New table DDL:

CREATE TABLE [dbo].[Karthik](
    [Empid] [int] IDENTITY(1,1) NOT NULL,
    [name] [varchar](50) NOT NULL,
    [sal] [money] NOT NULL,
    [expsal] [money] NOT NULL
) ON [PRIMARY]

New proc:


ALTER PROCEDURE InsertSalary
    -- Add the parameters for the stored procedure here
    @name varchar(50),
    @newsal money
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;
    DECLARE @maxempid int
    DECLARE @lastsal money
   
    SELECT @maxempid = MAX(empid) FROM Karthik

    IF (@maxempid IS NOT NULL)
        BEGIN
            SELECT @lastsal = sal FROM Karthik WHERE empid = @maxempid
           
            INSERT INTO Karthik (name, sal, expsal)
            SELECT @name, @lastsal, @newsal - @lastsal FROM Karthik WHERE empid = @maxempid
           
            UPDATE Karthik SET sal = @newsal WHERE empid = @maxempid
        END
    ELSE
    BEGIN
            -- this is a new employee record, so insert it
            INSERT INTO Karthik (name, sal)
            VALUES (@name, @newsal)
            -- default value is already set for expsal, no need to insert it here
    END
END
GO