7.3. Joins
Joining two or more tables of data is a powerful feature in the relational model. The SQL procedure enables you to join tables of information quickly and easily. Linking one piece of information with another piece of information is made possible when at least one column is common to each table. A maximum of 32 tables can be combined using conventional (inner) join techniques, as opposed to a maximum of two tables at a time using outer join techniques.
This chapter discusses a number of join topics including why joins are important, the differences between the various join techniques, the importance of the WHERE clause in creating joins, creating and using table aliases, joining three or more tables of data, outer (left, right, and ...
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