Ivor Horton's Beginning Java™ 2, JDK™ 5th Edition

24.2. Introducing SQL

Structured Query Language (SQL) is accepted internationally as the official standard for relational database access. A major reason for the acceptance of SQL as the relational query language was the move toward client/server architectures that began in the late 1980s.

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Not all versions and dialects of SQL are created equal, however. As vendors have incorporated SQL into their products, extensions to the grammar have often been added. That was convenient for the database vendors but tough for anyone else trying to work with more than one database vendor. To ensure SQL's place as a standard for database access, organizations like the ISO and ANSI have worked with the industry to develop standards for SQL. The current ISO operating standard is SQL-92, to which JDBC adheres. Conformance to the standard does not guarantee that your SQL will work in every case though. A database system that is in conformance with the standard for SQL is not obliged to implement all the capabilities that the standard defines. Indeed, most database systems do not do so.

SQL is different from other programming languages that you may be familiar with in that it is declarative, not procedural. In other words, you don't use SQL to define complex processes; you use SQL to issue commands that define and manipulate data.

The first thing that strikes you about SQL is that it is very readable. The way that each query is structured reads like a sentence in English. The syntax is easy ...