Chapter 2. SQL Fundamentals
In This Chapter
Clearing up SQL misconceptions
Taking a look at the different SQL standards
Getting familiar with standard SQL commands and reserved words
Representing numbers, characters, dates, times, and other data types
Exploring null values and constraints
Putting SQL to work in a client/server system
Considering SQL on a network
SQL is a flexible language that you can use in a variety of ways. It's the most widely used tool for communicating with a relational database. In this chapter, I explain what SQL is and isn't — specifically, what distinguishes SQL from other types of computer languages. Then I introduce the commands and data types that standard SQL supports and explain key concepts: null values and constraints. Finally, I give an overview of how SQL fits into the client/server environment, as well as the Internet and organizational intranets.
What SQL Is and Isn't
The first thing to understand about SQL is that SQL isn't a procedural language, as are BASIC, C, C++, C#, and Java. To solve a problem in one of those procedural languages, you write a procedure that performs one specific operation after another until the task is complete. The procedure may be a linear sequence or may loop back on itself, but in either case, the programmer specifies the order of execution.
SQL, on the other hand, is nonprocedural. To solve a problem using SQL, simply tell SQL what you want (as if you were talking to Aladdin's genie) instead of telling the ...