A SQL Overview

As you explore Crystal's SQL commands, you'll explore some of the areas of the SQL language. The subject of SQL is huge (not to mention a little on the dry side) and could easily fill volumes of books. Rather than explore the whole of SQL (which is beyond the scope of this book), this chapter explores the most frequently used areas of SQL, especially those areas of most interest to the report developer.

Where Did SQL Come From?

SQL (or structured query language) began as an IBM language. In 1988, the American National Standards Institute (ANSI) and the International Organization for Standardization (ISO) standardized SQL. The standard became known as ISO-ANSI SQL.

In 1992, a new version of the ANSI-ISO standard was released, containing a much richer set of functionality for commercial implementations. The U.S. National Institute of Standards and Technology (NIST) has required that most database vendors be compliant with the 1992 ANSI-ISO SQL (known as ANSI 92 Entry Level).

Thus, when talking about SQL, we're talking about the 1992 version of the language.

To get you started in the world of SQL programming, there are four basic SQL statements:

• SELECT

• INSERT

• UPDATE

• DELETE

With Crystal Reports' SQL commands, the only one of the above commands that you can use is SELECT. The SELECT statement allows you to retrieve (or view) data from a database.

Note

The other statements modify the database, which is functionality that is not available in Crystal Reports. As stated in Chapter 1, in no way can Crystal Reports alter the data within your database.

With that said, let's jump into Crystal Reports and get you building your first query files.