SQL stands for Structured Query Language and it is this is a structured query language. The programming language is ANSI and ISO is standardized and understood by most database systems. The three most popular SQL databases are MySQL, PostgreSQL, MaxDB, the largest commercial supplier in this field are Oracle and IBM. In any serious database is usually done each query, each deletion and each entry on SQL. Due to the huge amount of SQL language for this standard, there is no serious competition.
SQL was developed in the late 70 years at IBM in San Jose. Originally it was a so-called nonprocedural language, without any loops, functions or subroutines. In actual sense, one can with SQL not talk about a programming language. Accordingly, it is easy to learn. The commands are composed of data definition language (DDL) and Data Manipulation Laguage (DML), whereby via DDL defines the database structure, DML is then used to manipulate the data they contain.
To work with SQL you should be familiar with set theory, since relational databases accessible volume and group-oriented. It should be noted that almost every commercial SQL database product since individual characteristics in programming, and therefore has the standard more or less compatible. In all SQL commands are expressed textually, that is, you can rely on no graphics support. Also function as a scaffold always English key words for simple requests. These are reserved and can not be used elsewhere, such as a description of table or column name.