How to determine largest value comparing two or multiple columns using T-SQL

The below function can be used as a alternate for GREATEST() function in MYSQL:

Create a function with below code in your SQL SERVER database:

Below function compares 11 columns in a table.

CREATE FUNCTION dbo.fnGreatest
   (  @Value0  sql_variant,
      @Value1  sql_variant,
      @Value2  sql_variant,
      @Value3  sql_variant,
      @Value4  sql_variant,
      @Value5  sql_variant,
      @Value6  sql_variant,
      @Value7  sql_variant,
      @Value8  sql_variant,
      @Value9  sql_variant,
      @Value10  sql_variant
    )
   RETURNS sql_variant
AS
   BEGIN
     
      DECLARE @ReturnValue sql_variant

      DECLARE @MaxTable table
         (  RowID      int  IDENTITY,
            MaxColumn sql_variant
         )

        INSERT INTO @MaxTable VALUES ( @Value0 )
        INSERT INTO @MaxTable VALUES ( @Value1 )
        INSERT INTO @MaxTable VALUES ( @Value2 )
        INSERT INTO @MaxTable VALUES ( @Value4 )
        INSERT INTO @MaxTable VALUES ( @Value5 )
        INSERT INTO @MaxTable VALUES ( @Value6 )
        INSERT INTO @MaxTable VALUES ( @Value7 )
        INSERT INTO @MaxTable VALUES ( @Value8 )
        INSERT INTO @MaxTable VALUES ( @Value9 )
        INSERT INTO @MaxTable VALUES ( @Value10 )

       SELECT @ReturnValue = MAX(MaxColumn)
      FROM @MaxTable

      RETURN @ReturnValue

   END
GO








SELECT fnGreatest(date1,date2,date3.....date11)  from <tablename>