Structured Query Language

This page gives some basic information about SQL. Some persons pronounce it as "es que el" and others talk about "sequel", so it is not clear to me which one is right, but to me it's not really an issue. This page will only give very limited information about this language and is certainly not a tutorial, because there already are many well written SQL tutorials available on the internet. So there's no point for me to add another one. At the bottom of this page links to some very nice SQL tutorials can be found.


SQL is an abbreviation for Structured Query Language. SQL is used to communicate with a database. It can be seen as a standard language for relational database management systems (RDBMS's). Many tasks can be done using this language. Data can be added, updated, deleted and ofcourse retrieved amongst others.

The most common used relational database management systems like for instance Oracle, Sybase, Microsoft SQL Server, Microsoft Access and Ingres use SQL. The Structured Query Language can be seen as a wide spoken language understood by many databases. But most of these databases have their own dialect within the language. Most databases have additional proprietary extensions that are usually only used on their system.

In the mosts cases the standard SQL commands, which are understood by almost any dabase, are suitable. Examples of these standard commands are: SELECT, INSERT, UPDATE, DELETE, CREATE and DROP. The database specific commands are mostly used by database administrators or by at least advanced database users.

Standard SQL Commands

As mentioned earlier SQL is used to access a database. Below is list of standard SQL commands, which should work on all databases that use SQL.

  1. SELECT, to select data from a database table
  2. INSERT, to insert data into a database table
  3. UPDATE, to update data within a database table
  4. DELETE, to delete data from a database table
  5. CREATE, to create a database table
  6. DROP, to drop (delete) a database table and its contents


Oracle extended its variation of SQL that much, that it became a new language. PL/SQL is a procedural language based on SQL. PL/SQL is short for Procedural Language / Structured Query Language. With PL/SQL it possible to do things within the database in places where SQL is too limited. PL/SQL is a valuable extension to the Structured Query Language that makes it possible to have loops, certain queries only to be executed under certain circumstances and many, many more...


MySQL started as an open source database. The latest versions of this database perform very well and in many situations the possibilities of this database are suitable enough. MySQL is often combined with PHP scripts.


More information about SQL can be found on these sites:

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