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DB2® Universal Database for OS/390® Version 7.1 Certification Guide by Susan Lawson, Richard Yevich

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Data Retrieval

SQL is based on mathematical principles, specifically set theory and relational algebra. The data is stored in the database as unordered sets of data records. SQL is a set-oriented language and many of its language elements are directly related to relational algebraic terms, such as PERMUTATION, PROJECTION, RESTRICTION, and JOIN.

A set of data is represented in a DB2 database as a table or a view and is stored in a DB2 table without regard to order. To retrieve data in a particular order, an ORDER BY phrase must be added to a SELECT statement. Similarly, if the data is to be grouped, then a GROUP BY phrase must be added to the statement.

Now, let's review the DB2CERT database design defined in the previous chapter and manipulate ...

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