Too Long; Didn't Read
There is a lot of information about different T-SQL features about various life hacks and best practices in this language. I want to tell you about equally useful, but less popular tips for working with the language. A primary key should be specified during table creation to guarantee that all its records have primary key values. Nullable subqueries should not be used in "NOT IN" conditions. A WHERE clause condition that uses NOT IN with a subquery will have unexpected results if that subquery returns NULL.