T-SQL Querying

Chapter 3. Multi-table queries

This chapter’s focus is multi-table queries. It covers subqueries, table expressions, the APPLY operator, joins, and the relational operators UNION, EXCEPT, and INTERSECT.

Chapters 1 and 2 provided the foundation for the rest of the book. Chapter 1, “Logical query processing,” described the logical layer of T-SQL, and Chapter 2, “Query tuning,” described the physical layer. Each layer was described separately to emphasize its unique role—the logical layer’s role is to define meaning, and the physical layer’s role is to implement, or carry out, what the logical layer defines. The physical layer is not supposed to define meaning. Starting with this chapter, the coverage relies on the foundation provided in the previous ...