A TechNet article I liked on what’s new in SQL Server Agent for SQL Server 2005: security, proxy accounts, shared schedules, WMI alerts and Database Mail.
SQL SERVER – FIX : Error 15023: User already exists in current database.
Error 15023: User already exists in current database. I fix it with sp_change_users_login, using Report, Auto_Fix or Update_One to link the user to a login.
SQL SERVER – Primary Key Constraints and Unique Key Constraints
Primary Key and Unique Key both enforce uniqueness, but they differ in the index they create and in NULL handling. Here are the differences and the scripts.