How to permanently change first day of week in SQL Server

>> This customer ALWAYS starts their week on monday

Then you need to run the below statement at the beginning of all your sessions

SET DATEFIRST 1

>>  Is there a way to change it globably once?

Yes.. if you have the appropriate Language set whose Week starts on Monday..

SELECT * FROM sys.syslanguages

You can alter the login to begin with a Default Language like

ALTER LOGIN ur_login WITH DEFAULT_LANGUAGE = us_english

us_english has First day of week as Monday..

Hope this helps

Is there a way to change the default week start for a language?

Yes you can control it.
You need just to define a specific Language for each login used to connect to database.
for example for user account "sa" you can open Security->.Logins->sa and change the language of this user to "British English" (other languages and their values for first day of the week is available from

EXEC sys.sp_helplanguage

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>> You need just to define a specific Language for each login used to connect to database.
for example for user account "sa" you can open Security->.Logins->sa and change the language of this user to "British English

This is what I have suggested earlier using ALTER LOGIN statement..

>> change the language of this user to "British English" (other languages and their values for first day of the week is available from

Can you kindly let me know how to change the starting week for a particular language in SQL Server or OS..

You are right, It is not allowed to change the starting week for particular language in SQL Server