SQL (Standard Query Language) is a language for manipulating databases developed in the 70s by IBM. All data management systems use SQL to access data or to communicate with a data server. RDBMS is the core platform for SQL, and for all other modern database languages such as Oracle, MS SQL Server, IBM DB2, MySQL, and Microsoft Access, PostgreSQL, SQLite, Firebird, and many more. SQL (Standard Query Language) is born as a result of the mathematical work of Codd, who founded the work of relational databases, three types of manipulations on the database:
• The maintenance of tables: create, delete, and modify the table structure.
• The manipulation of databases: Selecting, modifying, deleting records.
• The management of access rights to tables: Data control: access rights, commit the changes.
The advantage of SQL is that it is a manipulation language standard databases, you can use on any database, even if, at first, you do not know its use. Thus, with SQL you can manage an Access database, but Paradox, dBase, SQL Server, Oracle or Informix example (the database most used). SQL base is RDBMS. Example of (RDBMS) Relational database management system (i.e. MySQL, MS Access, SQL Server ). MySQL, one of the most famous SQL distributions used by the majority of the scripts on the Internet.
Warning: The SQL language has often been implemented in different ways. The basic commands are always the same but sometimes variations or extensions. The version of SQL implemented in Access can sometimes be a bit different from the version which is ANSI standard version.
On the one hand, the structure and data manipulation have become very complex. For an application of medium size, the database contains more than thirty tables often highly interconnected. It is therefore out of the question to manipulate data algorithmically traditional. An SQL query in a simple logical language therefore advantageously replaces dozens of lines in a programming language such as C or COBOL.
On the other hand, the client-server architecture is omnipresent. While the client station executes the code in the application manager, in particular, the GUI, the server optimizes the handling and control of data. In addition, applications must be portable and manage virtual data that is to say from any server. Develop an application in a heterogeneous environment is only possible because the communication between the client application and the server is performed by standard SQL primitives.
Finally, to develop applications (even on a PC) have become increasingly complex. Profile programmer has changed significantly. He must now process data more voluminous, integrating techniques for handling interfaces, event control logic and object-oriented programming, all this in the context of a client-server architecture where quotient operating systems and protocols for heterogeneous networks. Access and manipulation of data is only one aspect of the design and implementation of programs.
It seeks to acquire a powerful development environment that supports a large number of related tasks. Development tools have emerged to allow the developer to concentrate on the application itself: generators screens, reports, queries, design assistance program, connecting to remote databases via networks. In all of these tools, the simplicity and standardization of SQL are SQL is used whenever a definition, manipulation, or control data is needed. SQL is a central element between the various components of a development environment in a client-server architecture.