Introduction to SQL
Today, we take a look at what SQL is and describe its major features and benefits. This is chapter one of McGraw-Hill/Osborne's SQL: The Complete Reference (ISBN 0-07-222559-9, 2004) by James R. Groff and Paul N. Weinberg.
The SQL language and relational database systems based on it are one of the most important foundation technologies in the computer industry. Over the last two decades, SQL has grown from its first commercial use into a computer product and services market segment worth tens of billions of dollars per year, and SQL stands today as the standard computer database language. Literally hundreds of database products now support SQL, running on computer systems from mainframes to personal computers and even handheld devices. An official international SQL standard has been adopted and expanded twice. Virtually every major enterprise software product relies on SQL for its data management, and SQL is at the core of the database products from Microsoft, Oracle, and IBM, the three largest software companies in the world. SQL is also at the heart of open-source database products that are helping to fuel the popularity of Linux and the open-source movement. From its obscure beginnings as an IBM research project, SQL has leaped to prominence as both an important computer technology and a powerful market force.
What, exactly, is SQL? Why is it important? What can it do, and how does it work? If SQL is really a standard, why are there so many different versions and dialects? How do popular SQL products like SQL Server, Oracle, Informix, Sybase, and DB2 compare? How does SQL relate to Microsoft standards, such as ODBC and COM? How does JDBC link SQL to the world of Java and object technology? What role does it play in the emerging “web services” architecture and the competing web services architectures from the Microsoft and Java-based camps? Does SQL really scale from mainframes to handheld devices? Has it really delivered the performance needed for high-volume transaction processing? How will SQL impact the way you use computers, and how can you get the most out of this important data management tool?
Structured Query Language (SQL)
The Structured Query Language (SQL) forms the backbone of
most modern database systems. These links provide the best resources on
the Net for neophytes and expert database administrators alike!
Articles & Resources
Book
Review: SQL Cookbook
O'Reilly's SQL Cookbook is the best reference I've seen for skilled
SQL developers. Modeled after a true cookbook, it offers many short
snippets of SQL code designed to solve specific problems. You can pick
and choose the ingredients you need to help complete your SQL project.
Retrieving
Data with the SELECT Statement
The SELECT command is the most commonly used command in SQL. It allows
database users to retrieve the specific information they desire from
an operational database.
Introduction
to SQL
The Structured Query Language (SQL) is the language of databases. All
modern relational databases, including Access, FileMaker Pro, Microsoft
SQL Server and Oracle use SQL as their basic building block. In fact,
it’s often the only way that you can truly interact with the database
itself.
Using
Self-Joins in SQL
Did you know that you can use a self-join to simplify nested SQL queries
where the inner and outer queries reference the same table? Let's take
a look at an example.
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