SQL Clearly Explained, 2nd Edition

4. Simple SQL Retrieval

It may seem a bit backwards to talk about retrieval before creating a database or entering data, but much of SQL's data modification syntax relies on finding data to be changed. You will therefore find it easier to work with modification statements if you are first familiar with retrieving data. We are therefore going to assume that someone else has created a database and loaded it with data for our use.

SQL has one command for retrieving data: SELECT. This is nowhere as restrictive as it might seem. SELECT contains syntax for choosing columns, choosing rows, combining tables, grouping data, and performing some simple calculations. In fact, a single SELECT statement can result in a DBMS performing any or all of the relational ...