As we said, SQL
(Structured Query language) is the language of choice for most
modern multi-user, relational databases. That is because SQL provides
the syntax and idioms (language) you need to talk to (query) relational
databases in a standardized, cross-platform/product way
(structured).
The beauty of SQL is that it idiomizes the
relational model. Rather than refer to data as a set of pointers,
SQL provides predefined procedures to allow you to use any value
in a table to relate other tables in a database. So long as
a database is structured using the relational model, SQL will
be a natural fit because SQL was designed to make sense in
a relational system. SQL by its very design is a language that
can be used to talk about relating tables.
For the rest of Part One and Two, we will examine
how you will use SQL to access relational databases. However, first
we should say a little bit about the structure of SQL databases before
we plunge into usage.
SQL databases (most modern relational databases)
as you will recall, are composed of a set of row/column-based "tables", indexed by a
"data dictionary". To access data in the tables, you simply use SQL
to navigate the system and produce "views" based on search criteria
defined in the SQL query.
Okay, that was quite a bit of jargon all at once.
Let's step back for a moment and look at each of these terms.
