In part 2, Paulo R. Pereira compares IN, EXISTS, SOME and JOIN plans, and shows again that the SQL Server Engine knows the best plan for a query.
SQL SERVER – Subquery or Join – Various Options – SQL Server Engine knows the Best
Subquery or join, IN or EXISTS? Four queries return the same result, and the execution plans show the SQL Server engine knows the best way to run them.
Aggregate Before the Join: Shrinking Rows Early With GROUP BY
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.