SQL query long essay
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Abreu, et.al. (2006) described that the relational model came about as a result of E. Codd’s research at IBM during the sixties. The SQL, originally named SEQUEL (Structured English Query Language), was implemented in an IBM prototype (SEQUEL-XRM), during the mid-seventies. Some years later, a subset of this language was implemented in IBM’s System-R.
In 1979, ORACLE emerged as the first commercial DBMS based on SQL, followed by several other products such as SQL/DS, DB2, DG/SQL, SYBASE, INTERBASE, INFORMIX, UNIFY. Even those which had not originally implemented SQL as their base query language, offered SQL interfaces such as INGRES, ADABAS, SUPRA, IDMS/R. As a result of this process, Standard Query Language became a de facto standard.
In late 1982, American National Standards Institute (ANSI) H23 begins to standardize SEQUEL which is version of the relational data model through the IBM language. In 1986, renamed SQL by H2, basic SQL was completed and become an American National Standard and soon an ISO standard.
In 1989, the first version of the SQL standard was revised and an addendum, which included main improvements on referential integrity issues, was published. Meanwhile, ANSI brought out a standard for embedded SQL.
In the early nineties, a new version, known as SQL2 or SQL-92, was published by ISO. Both the semantic capabilities of the language and error management were then considerably improved. That standard was complemented a few years later, with the approval of SQL/CLI (Call-Level Interface) and SQL/PSM (Persistent Stored Modules). SQL became a complete computational language, with features such as control structures and exception handling.
During the last half of the nineties, SQL was extended by the inclusion of object-oriented capabilities. The resulting standard was divided into several parts. This version, previously known as SQL3 and then finally called SQL:1999, incorporated features such as new basic data types for example very large objects, user defined data types, recursive query operators, sensitive cursors, tables generalization and user roles.
According to Abreu, et.al. (2006), The latest version of the standard is the SQL:2003, which is there are major revisions and extensions to most parts of the SQL:1999 standard. This version contains SQL/XML which is XML related specifications, new basic data types such as bigint, multiset and XML, enhancements to SQL-invoked routines, extensions to the CREATE TABLE statement, there are new MERGE statement, schema object which is the sequence generator and two new sorts of columns for identity and generated. He also produced the Table 1 as summarizes the evolution of SQL.