SET Datefirst - TSQL Tutorial

SET Datefirst - sets the first day of the week to a number from 1 through 7.

SET Datefirst Syntax:

SET DATEFIRST { number | @number_variable } ;

SET Datefirst Example:

SET DATEFIRST 1 ;

Messages:
Command(s) completed successfully.

SELECT @@DATEFIRST AS 'First Day';

Result:
1