Rules for SQL Server Logins, Users, Roles, and Passwords

Microsoft® SQL Server™ logins, users, roles, and passwords can contain from 1 to 128 characters, including letters, symbols, and digits, (for example Andrew-Fuller, Margaret Peacock, or 13&#57abc). Therefore, Microsoft Windows NT® or Microsoft Windows® 95/98 usernames can be used as SQL Server logins. However, certain symbols can be used only in Transact-SQL statements if the login, user, role, or password is delimited with double quotation marks (“), or square brackets ([ ]). Use delimiters in Transact-SQL statements when the SQL Server login, user, role, or password:

• Contains, or begins with, a space character.
• Begins with the $ or @ character.

Note It is not necessary to specify delimiters when entering logins, users, roles, and passwords into the text boxes of the SQL Server graphical client tools, such as SQL Server Enterprise Manager.

Additionally, a SQL Server login, user, or role cannot:

• Contain a backslash (\) character, unless referring to an existing Windows NT user or group. The backslash separates the Windows NT computer or domain name from the username.
• Already exist in the current database (or master, for logins only).
• Be NULL, or an empty string (““).

See Also

Delimited Identifiers