Bagikan melalui

  • Artikel

CREATE USER (Transact-SQL)

Adds a user to the current database.

Topic link iconTransact-SQL Syntax Conventions

Syntax

CREATE USER user_name 
    [ { { FOR | FROM }
      { 
        LOGIN login_name 
        | CERTIFICATE cert_name 
        | ASYMMETRIC KEY asym_key_name
      } 
      | WITHOUT LOGIN
    ] 
    [ WITH DEFAULT_SCHEMA = schema_name ]

Arguments

  • user_name
    Specifies the name by which the user is identified inside this database. user_name is a sysname. It can be up to 128 characters long.

  • LOGIN login_name
    Specifies the SQL Server login for which the database user is being created. login_name must be a valid login in the server. When this SQL Server login enters the database it will acquire the name and ID of the database user that is being created.

  • CERTIFICATE cert_name
    Specifies the certificate for which the database user is being created.

  • ASYMMETRIC KEY asym_key_name
    Specifies the asymmetric key for which the database user is being created.

  • WITH DEFAULT_SCHEMA **=**schema_name
    Specifies the first schema that will be searched by the server when it resolves the names of objects for this database user.

  • WITHOUT LOGIN
    Specifies that the user should not be mapped to an existing login.

Remarks

If FOR LOGIN is omitted, the new database user will be mapped to the SQL Server login with the same name.

If DEFAULT_SCHEMA is left undefined, the database user will use dbo as its default schema. DEFAULT_SCHEMA can be set to a schema that does not currently exist in the database. DEFAULT_SCHEMA can be set before the schema that it points to is created. DEFAULT_SCHEMA cannot be specified when you are creating a user mapped to a Windows group, a certificate, or an asymmetric key.

Important

The value of DEFAULT_SCHEMA is ignored if the user is a member of the sysadmin fixed server role. All members of the sysadmin fixed server role have a default schema of dbo.

The WITHOUT LOGIN clause creates a user that is not mapped to a SQL Server login. It can connect to other databases as guest.

The names of users that are mapped to SQL Server logins, certificates, or asymmetric keys cannot contain the backslash character (\).

CREATE USER cannot be used to create a guest user because the guest user already exists inside every database. You can enable the guest user by granting it CONNECT permission, as shown:

GRANT CONNECT TO guest;
GO

Information about database users is visible in the sys.database_principals catalog view.

Warning

Beginning with SQL Server 2005, the behavior of schemas changed. As a result, code that assumes that schemas are equivalent to database users may no longer return correct results. Old catalog views, including sysobjects, should not be used in a database in which any of the following DDL statements have ever been used: CREATE SCHEMA, ALTER SCHEMA, DROP SCHEMA, CREATE USER, ALTER USER, DROP USER, CREATE ROLE, ALTER ROLE, DROP ROLE, CREATE APPROLE, ALTER APPROLE, DROP APPROLE, ALTER AUTHORIZATION. In such databases you must instead use the new catalog views. The new catalog views take into account the separation of principals and schemas that was introduced in SQL Server 2005. For more information about catalog views, see Catalog Views (Transact-SQL).

Permissions

Requires ALTER ANY USER permission on the database.

Examples

A. Creating a database user

The following example first creates a server login named AbolrousHazem with a password, and then creates a corresponding database user AbolrousHazem in AdventureWorks2008R2.

CREATE LOGIN AbolrousHazem 
    WITH PASSWORD = '340$Uuxwp7Mcxo7Khy';
USE AdventureWorks2008R2;
CREATE USER AbolrousHazem FOR LOGIN AbolrousHazem;
GO

B. Creating a database user with a default schema

The following example first creates a server login named WanidaBenshoof with a password, and then creates a corresponding database user Wanida, with the default schema Marketing.

CREATE LOGIN WanidaBenshoof 
    WITH PASSWORD = '8fdKJl3$nlNv3049jsKK';
USE AdventureWorks2008R2;
CREATE USER Wanida FOR LOGIN WanidaBenshoof 
    WITH DEFAULT_SCHEMA = Marketing;
GO

C. Creating a database user from a certificate

The following example creates a database user JinghaoLiu from certificate CarnationProduction50.

USE AdventureWorks2008R2;
CREATE CERTIFICATE CarnationProduction50
    WITH SUBJECT = 'Carnation Production Facility Supervisors',
    EXPIRY_DATE = '11/11/2011';
GO
CREATE USER JinghaoLiu FOR CERTIFICATE CarnationProduction50;
GO

D. Creating and using a user without a login

The following example creates a database user CustomApp that does not map to a SQL Server login. The example then grants a user adventure-works\tengiz0 permission to impersonate the CustomApp user.

USE AdventureWorks2008R2 ;
CREATE USER CustomApp WITHOUT LOGIN ;
GRANT IMPERSONATE ON USER::CustomApp TO [adventure-works\tengiz0] ;
GO

To use the CustomApp credentials, the user adventure-works\tengiz0 executes the following statement.

EXECUTE AS USER = 'CustomApp' ;
GO

To revert back to the adventure-works\tengiz0 credentials, the user executes the following statement.

REVERT ;
GO