Aggregate before the join only when the grouping preserves the required customer result. This private lab checks NULLs, missing matches, duplicate dimensions, complete outputs, actual plans, and reads.
A Learning Path for a New SQL Developer
A new SQL developer can build skill in a clear order: relational basics, T-SQL, data modeling, plans, testing, and safe deployment habits.
Replacing Old Syntax in Legacy T-SQL
Modernize legacy T-SQL by replacing old joins, TEXT columns, and fragile RAISERROR forms with clear, tested alternatives.
UPDATE With a JOIN: Changing Rows From Another Table Safely
Use UPDATE with a JOIN safely, reject duplicate source keys, compare subquery and MERGE behavior, and verify the affected rows.
SQL SERVER – 2008 Star Join Query Optimization
Star Join Query Optimization in SQL Server 2008 Enterprise Edition uses bitmap filtering to speed up data warehouse queries that join fact tables.
SQL SERVER – Understanding Table Hints with Examples
What are hints in SQL Server and when should you use them? Understanding table hints with examples, plus a word of caution about overriding the optimizer.
SQL SERVER – Interesting Observation – Query Hint – FORCE ORDER
A junior developer used the FORCE ORDER query hint without knowing what it does. Here is how it works and how much this one hint can change performance.