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Inside Microsoft® SQL Server™ 2005: T-SQL Querying by Dejan Sarka, Lubor Kollar, Itzik Ben-Gan

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Logical Query Processing Phase Details

This section describes the logical query processing phases in detail by applying them to the given sample query.

Step 1: Performing a Cartesian Product (Cross Join)

A Cartesian product (a cross join, or an unrestricted join) is performed between the first two tables that appear in the FROM clause, and as a result, virtual table VT1 is generated. VT1 contains one row for every possible combination of a row from the left table and a row from the right table. If the left table contains n rows and the right table contains m rows, VT1 will contain n × m rows. The columns in VT1 are qualified (prefixed) with their source table names (or table aliases, if you specified ones in the query). In the subsequent steps (step ...

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