I have Sql Server 2008 installed on a server (let's say Server1) in a Domain (let's say AD). I also have a domain account called AD\Sql1. This is not an Admin account on the Domain (AD), but I want it to be an admin on the Server1. And then create a login on Sql Server for that Domain account (not local account).

How do I do that?


  1. The user AD\Sql1, I want him as Admin on Server1. For that, do I just create a local account with the same user name (let's say, Server1\Sql1) and make the local account an Admin on the machine. Will that local account be automatically mapped to the domain account with the same name? May be I should add here that CREATE LOGIN [AD\Sql1] FROM WINDOWS did not work for me. I tried and got an error saying user does not exist in Windows (something like that)
  2. Now, if the above technique works. Lets assume, AD\Sql1, becomes an Admin on Sever1. So, in theory I do not need to create a Sql Login for that Windows Domain account on the Sql Server, right? All the local admins that are part of BUILTIT\Admins automatically have sysadmin access to Sql Server, right?

Where did I go wrong? Please share any URLs that could explain this concept better.

Edit: I should also add that Question 1 and 2 are important independently. I know how to add a domain/windows account as sysadmin. But I am interested in how mapping works between Domain and local accounts. My goal here is not how to add a local account as sysadmin, I can do that pretty quickly. My intention is not to be rude, but be as clear as possible. If my question is still not clear, please let me know, so I could add more details.


Edit: Grammar

2 Answers 2


Don't create a local account with the same name as the domain account. If you want to add a domain login as a sql admins do as follows:

  • create a login for the domain account: create login [AD\Sql1] from windows;
  • add the login to sysadmin group: exec sp_addsrvrolemember 'AD\Sql1', 'sysadmin';

Done. You would achieve the same result if you'd simply add the AD\Sql account to the local administrators via net localgroup Administrators /add AD\Sql1 (from a CMD shell) but that is not the correct solution as it grants AD\Sql1 all NT administrator privileges in addition to granting him SQL admin, which is not stated as a requirement therefore is unnecessary elevation. BTW the rule that members of the local Administrators group are SQL admins is not implicit, is an explicit privilege granted by default during SQL Setup and it can be revoked so you have to check for it.

  • Thank you, this comment has some info that I could use. But I have a follow up question. when I tried to add Sql login using CREATE LOGIN [AD\Sql1] FROM WINDOWS, I got an error saying that the user does not exist in Windows. So, I had to add him as used to local machine (then it works).
    – UB01
    Mar 28, 2012 at 18:26
  • I'll look into the point that you mentioned about '..the local admins being by default sysasmins on the machine'. Thank you, I will read up on that. But how does the mapping work? Between Domain accounts and local accounts with the same name.
    – UB01
    Mar 28, 2012 at 18:31
  • If machine where instance of SQL Server installed, is part of domain you should be able to add domain account without any issue.
    – JackLock
    Mar 28, 2012 at 19:01
  • Okay, that's what I thought, but I kept getting this error: ...user could not be found in windows. May be there is something else going on. I will check again.
    – UB01
    Mar 28, 2012 at 19:11
  • 1
    I got an error saying that the user does not exist in Windows: that means your SQL host machine is not member of the AD domains, or member of a domain that trusts AD. You should add the machine to AD domain. You are now pursuing the so called 'NT mirrored accounts' approach (perhaps w/o knowing you're doing so...) and this is a wrong approach. Add the SQL hosting machine to the AD domain. Mar 28, 2012 at 19:12

Connect to your instance in SSMS. Expand security / logins. Rt-click add new login, put in the info. On server roles, grant it sysadmin if you want it to have total power over the SQL instance. Done. This account does not need to be local admin on your Windows machine to be sysadmin in SQL Server.

  • Thank you for the quick comment. I do understand the concept you conveyed in your response. My question (may be not very clear) is to understand how the relation (or mapping) works between Domain accounts and local accounts. And how that affects Sql Server.
    – UB01
    Mar 28, 2012 at 18:09
  • A SID is create in the master db for any accounts, domain or SQL Server only accounts. Mar 28, 2012 at 18:47
  • SID created for each account.. is a concept I understand. Let me give you an example: Is the account AD\Sql1 same as Server1\Sql1 on the server. Does each have a seperate Security ID that is mapped so that OS know that they are one and the same? Does this even happen? (I am only guessing, I do not know)
    – UB01
    Mar 28, 2012 at 18:59
  • I see. You are more trying to understand Windows creds I think. AD and local Windows accounts are not the same (even if name is the same). Here's some info about how domain SIDs, access tokens work. I hope this helps: technet.microsoft.com/en-us/library/cc785913(v=ws.10).aspx Mar 28, 2012 at 19:18
  • Thank you, I'll read that article and see if that helps me understand the concepts better.
    – UB01
    Mar 28, 2012 at 19:23

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