Overview of SQL:
SQL stands for Structured Query Language. It is a computer language specifically created for databases.
SQL is used to share and manage data, particularly the data that is found in relational database management systems - where the data is organized in tables, and where multiple files, each containing tables of data, may be related together by a common field. Using SQL, you can query (request information from databases), update and reorganize data, as well as create and modify the schema (structure) of a database system, and control access to the data.
SQL is pronounced one of two ways: "sequel" or "ess-queue-ell."
History of SQL:
In a paper written in 1970, titled "A Relational Model of Data for Large Shared Data Banks," Edgar F. Codd, a researcher for IBM, defined the relational database model, which became the basis for developing the SQL language.
Based on Codd's findings, in 1974 IBM began working on a new language for relational database management systems. The language was originally called SEQUEL, or Structured English Query Language. This project, dubbed System/R, went through a few implementations and revisions, and the name of the language was changed a few times before it was finally called SQL.
After beginning testing on SQL in 1978, IBM started developing commercial products, including SQL/DS (1981) and DB2 (1983). Other vendors followed suit, announcing their own commercial SQL-based offerings. These included Oracle, which released its first product in 1979, as well as Sybase and Ingres.
If you're wanting to learn SQL but you are starting completely from scratch with very little programming background, you may benefit from taking courses offered by your local community college or university. Otherwise, you could take advantage of many free online tutorials or paid-for distance-learning courses.
First, you should check out the Learning SQL E-Course offered by Mike Chapple, About.com's Databases Guide.
Here are some examples of other free tutorials:
If you're interested in distance-learning courses (for a fee), I would recommend the International Webmasters Association's (IWA) Introduction to SQL (Using Access) or Introduction to SQL (Using MySQL).
I've taken IWA courses before. The SQL ones are only four weeks long, but they're more structured than self-learning tutorials because the courses are instructor-led and involve completing specific assignments once a week. You'd be surprised how much you can learn in such a short timespan.
Useful books on SQL for beginners include:
- Sam's Teach Yourself SQL in 24 Hours - the contents of this book are available online for free;
- SQL: A Beginner's Guide;
- SQL in a Nutshell.
Check your local library to see if they carry these or other introductory SQL books.
Careers that Require SQL Skills:
Here are some of the types of positions that require you to have SQL skills:
- database developer;
- database administrator (DBA);
- data analyst
- data warehouse engineer
- SQL reports writer