Data Manipulation
There are two varieties of data manipulation operation, collectively called DML, data manipulation language:
Data retrieval: finding the particular data you want
Data modification: adding, removing, or changing the data
Data retrieval operations (often called queries) search the database, fetch information you've requested in the most efficient way possible, and display it. All SQL queries are expressed using the keyword SELECT.
The rest of this chapter includes some simple SQL queries. Don't worry about the syntax right now: it'll be fully explained in Chapter 3 before you're expected to sit down at a computer terminal and replicate anything you see here. For now, just glance at the examples and results to get the flavor of ...
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