SQL: Query Language for Relational Databases

SQL is an acronym that stands for "Structured Query Language" and it's used primarily for retrieving and manipulating data stored in a relational database (relational databases are ones made up of separate tables that have explicit relationships between them so various elements can be selectively combined through queries). SQL is such a powerful language it is possible to create and destroy entire databases within seconds using only a few basic commands, plus SQL allows the combination of extremely large amounts of data quickly and efficiently.

Raymond Boyce and Donald Chamberlin developed the SQL language in the 1970s and initially named it “SEQUEL.” Their language was created to work with data stored in one of the very first relational databases called "System R." The underlying architecture of SQL was based on a research paper titled "A Relational Model of Data for Large Shared Data Banks," written by Edgar F Codd and published in 1970. (A group working at IBM were the first people to develop a relational database and Oracle was the first company to release one publicly.)

SQL can be pronounced in either of two ways (both equally correct): you can either say each letter aloud: "ess que ell" or simply pronounce the word "sequel." There are a few different “brands” or types of SQL currently in use by various companies: PostgreSQL, MySQL, Microsoft SQL, mSQL, PL/SQL, Transact-SQL, ANSI SQL, among others.

By learning SQL you will come to understand the basic structure of most modern databases; and you don't necessarily have to be a skilled programmer to use SQL since it was originally designed for database users rather than software engineers (it's ideal for accountants, architects, engineers, urban planners, etc.). Certain programming skills however will come in handy since advanced SQL commands can be quite complicated, and of course there is a special syntax one needs to follow, plus the use of relational operators (=, !=, >, <, >=, etc.) can sometimes be tricky.

There are many online SQL tutorials in case you would like to begin learning the language on your own. To get started familiarizing yourself, here is what a common SQL command looks like:

SELECT "column_name" FROM "table_name"

This command simply chooses pieces of information from a table. Here are many more common SQL commands:

CREATE, INSERT, WHERE, SUM, TRUNCATE, COUNT, MERGE, DELETE, DROP, NULL, DATE, TIME, GRANT, ORDER BY, FROM, JOIN, DENY, GROUP BY, NULL.

Keep in mind, using SQL is much more complicated than simply typing in one or two commands. However SQL does follow a “top-down” programming structure, meaning that things get more detailed as the command continues down the "page," and that there's a certain hierarchy involved, which does help to simplify learning the language a bit. The commands listed above include basics for retrieving and storing data, as well as some of the more advanced commands used for table construction and manipulation.

Relational database programming is a highly valued skill on the software job market today, and SQL is the most common language you would be working with. Most organizations and companies across the globe have huge quantities of data they need stored and manipulated in a myriad of ways, and if you're a programmer adept at making this data accessible and manageable, while being able to draw out whatever they need from it, you could be paid quite handsomely for your skills.

Author: Jason Earls,  Published: 2010-02-26
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