The origins of the SQL take us back to the 1970s when in the IBM laboratories, new database software was created - System R. And to manage the data stored in System R, the SQL language was created. At first, it was called SEQUEL, a name which is still used as an alternative pronunciation for SQL but was later renamed to just SQL.In 1979, a company called Relational Software, which later became Oracle, saw the commercial potential of SQL and released its own modified version, named Oracle V2.Now into its third decade of existence, SQL offers great flexibility to users by supporting distributed databases, i.e. databases that can be run on several computer networks at a time. Certified by ANSI and ISO, SQL has become a database query language standard, lying in the basis of a variety of well-established database applications on the Internet today. It serves both industry-level and academic needs and is used on both individual computers and corporate servers. With the progress in database technology, SQL-based applications have become increasingly affordable for the regular user. This is due to the introduction of various open-source SQL database solutions such as MySQL, PostgreSQL, SQLite, Firebird, and many more.SQL StandardThe SQL Standard has gone through a lot of changes during the years, which have added a great deal of new functionality to the standard, such as support for XML, triggers, regular expression matching, recursive queries, standardized sequences and much more. Due to SQL Standard's sheer volume, a lot of database solutions based on it, such as MySQL or PostgreSQL, do not implement the whole standard. In a lot of cases, the database behaviour for file storage or indexes is not well defined and it's up to the vendors of the various SQL implementations to decide how the database will behave. This is the reason why, even though all SQL implementations have the same base, they are rarely compatible.SQL Language elementsThe SQL language is based on several elements. For the convenience of SQL developers, all necessary language commands in the corresponding database management systems are usually executed through a specific SQL command-line interface (CLI).
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