SQL

To manage the data base data model most commonly used is the relational model and to communicate with the manager can use the SQL language

It is NOT a programming language, but a database management language that has the following characteristics:

• DDL (Data Definition Language)

  The DDL SQL provides commands for defining relation schemas, deleting and changing relationships schemes relationship

• DML (Data Manipulation Language)

  The DML SQL includes a query language based on both relational algebra and tuple relational calculation. It also includes commands to insert, delete, and modify tuples

• Integrity

  The DDL includes commands to specify integrity constraints that must meet the data stored in the database. Updates that violate integrity restrictions are rejected

• Definition of views

  The SQL DDL includes commands for defining views

• Transaction control

  SQL includes commands to specify the start and end of transactions

• Built-in SQL and dynamic SQL

  Built-in SQL and Dynamic SQL define how SQL statements can be incorporated into general-purpose programming languages such as C, C++, Java, PL/L, Cobol, Pascal or Fortran, among others

• Authorization
  The SQL DDL includes commands to specify access rights to relationships and views

Evolution of SQL

IBM developed the original version of SQL, called Sequel, as part of the System R project in the early 1970s by the San Jose, California

The Sequel language has evolved since then and its name has become SQL (Structured Query Language)

Today, many programming languages support the SQL language and have been set as the standard language for the use of relational databases

1981, IBM released the first commercial SQL-based program

1986, ANSI (American National Standards Institute) published a SQL standard, called SQL-86 or SQL1 and was confirmed by ISO (International Standards Organization) in 1987

1989 ANSI released an extension of the standard for SQL named SQL-89

1992, a new version of the standard called SQL-92 or SQL2 appeared

1999, a new version called SQL:1999 or SQL2000 appeared. In which regular expressions, recursive queries (for hierarchical relationships), triggers, and some object-oriented features were added

2003, a new version called SQL:2003 appeared. In which some XML features, changes in functions, standardization of the sequence object and autonumeric columns were added

2005, a new version called SQL:2005 appeared and corresponds to the ISO/IEC 9075-14:2005 standard. Defining how SQL can be used in conjunction with XML:

• Import and save XML data into a SQL database, manipulating it within the database and publishing conventional XML and SQL data in XML
• Facilities that allow applications to integrate into their SQL code the use of XQuery, XML query language published by the World Wide Web Consortium (W3C) for concurrent access to ordinary SQL data and XML documents

2008, a new version called SQL:2008 appeared. In which the use of the ORDER BY clause was added outside the cursors definitions. Including triggers of the INSTEAD OF type. And the inclusion of the TRUNCATE judgment

2011, a new version called SQL:2011 appeared. In which the temporary data (PERIOD FOR) and improvements in the window functions and the FETCH clause were added

2016, a new version called SQL:2016 appeared. In which the search was added using patterns, polymorphic table functions and compatibility with JSON files