What is the difference between DISTINCT and GROUP BY? They usually produce the same plan. Use GROUP BY for aggregates and DISTINCT to remove duplicates.
SQL SERVER – SQL Commandments – Suggestions, Tips, Tricks
My 20 SQL Commandments for SQL Server, rewritten from an Oracle article: know your data, test with realistic data, write identical statements, and more tips.
SQL SERVER – SQL Server 2005 Samples and Sample Databases (February 2007)
SQL Server 2005 Samples gave learners AdventureWorks and the smaller AdventureWorksLT. Why they mattered and where to find sample databases today.
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.
SQL SERVER – ReIndexing Database Tables and Update Statistics on Tables
ReIndexing Database tables with DBCC DBREINDEX and sp_MSforeachtable, then sp_updatestats to refresh statistics. Two scripts, including the one I prefer.