කෝඩ්හී පත්තර තුලින් relational model සහ relational languages (වීජ ගණිතය සහ කලනය) හදුන්වාදීම පුකාශකිරීමේ ප්‍රතිඵලයක් ලෙස වාණීජ සහ පර්යේෂණ සමූහයන්ට සම්පූර්ණ කරන ලඳ relational languages වල වෙළුම් සංවර්ධනයට වැදගත් අවස්ථාවක් විය. මෙම උත්සහයෙන් වැදගත් භාෂා තුතක් පැමිණියේය. එනම්

1. SQL (Structured Query Language, මෙය “එස්-කිවු-එල්” හෝ “සීකුවල්” ලෙස උච්චාරණය කරයි)
2. QBE (Query-by-Example)
3. UEL (Query Language)

SQL සහ QBE යන භාෂා දෙක බොහෝ සම කාර්යයන් සමඟ හැත්තෑව දශකයේ IBM සමා‍ගමේ නිපැයුමකි. QBE ප්‍රස්ථාරික වූ අතර SQL පෙළ පදනම් වූ භාෂාවකි. එසේම QUEL හී මූල භාෂාව INGRES වන අතර Berkeley හී කැලිෆෝනියා විශ්ව විද්‍යාලයේ දී හැත්තෑව දශකයේදී relational database management system සංවර්ධණය විය.

SQL IBM හී “System R research” නම් ව්‍යාපෘතියේ ශාඛාවකි. මෙම ව්‍යාපෘතියට Relational database system සහ SEQUEL භාෂාව සදවර්ධනයද ඇතුලත් විය. SEQUEL, SQL දක්වා වෙනස් වී හැත්තෑව දශකය අවසානයේදී පොදු වසමට මෙන්ම පළමුවෙන්ම Oracle සමාගමේ වාණීජ පද්දතියේ කොටසක් වුනි. එසේම 1981 දී IBM සමාගම SQL සමඟ SQL/DS යන වාණීජ database management system (DBMS) නිකුත් කලේය.

1986 දී ප්‍රථම SQL සඳහා ANSI ප්‍රමිතිය අනුමත විය. පසුව මෙය 1989 දී හා 1992 දී සංශෝධනය විය. එසේම 1980 සිට බොහෝ සැපයුම්කරුවන් විසින් SQL භාවිතා කිරීමට පටන් ගැනුනි.
මීට අමතරව mainframe වෙළුම් වල SQL භාවිතා කිරීමට පෙර බොහෝ සේවාලාභී/ සේවා දායක සහ පෞද්ගලික පරිගණක වෙළුම් වල SQL භාවිත කිරීමේ හැකියාව ලැබුණි. Sybase SQL Server, Microsoft SQL Server, IBM OS/2 Extended Edition Database Manager, DEC Rdb/VMS, Oracle Server for OS/2 (Khoshafian et al.) SQLBase, R:Base සහ dBASE උදාහරණ කිහිපයකි.
Relational database management systems බොහෝ විවිධ ලක්ෂණ සහ භාෂා හැකියාවයන්ට රුකුලකි. එසේම මෙම පහසුකම් සෑම පැත්තකම පිහිටා තිබේ.

The aftermath of the publication of Codd’s papers introducing the relational model and relational languages (Algebra & Calculus) were a great deal of activity in the commercial and research communities to develop implemented versions of relational languages. There are three must important languages to come out of this effort. These are,

1. SQL (Structured Query Language, it pronounced either “ess-cue-ell” or “sequel”)
2. QBE (Query-by-Example)
3. QUEL (Query Language)

SQL and QBE both originated at International Business Machines (IBM) during the seventies and perform many similar functions, although SQL is a textual language while QBE is graphical. QUEL is the original language of INGRES, a relational database management system developed during the seventies at the University of California, Berkeley.

SQL was the outgrowth of IBM’s System R research project. This project included the development of a relational database system and the language SEQUEL (Structured English Query Language). In the late seventies, SQL (changed from SEQUEL) became part of the public domain and was first available as a language for a commercial system from Oracle Corporation. In 1981, IBM released SQL/DS, which is a commercial database management system (DBMS) that supports SQL. In 1983, IBM released SQL as part of the DB2 DBMS.

In 1986, the first ANSI standard for SQL was approved. This standard was later revised (modestly) in 1989 and (significantly) in 1992. SQL is seems likely to remain, the only ANSI standard relational database language. Moreover, SQL is the de facto standard in business, since it is by far the relational language of choice in commercial systems. Numerous vendors have released implementations of SQL since 1980.

In addition to the mainframe versions of SQL listed previously, many client/server and personal computer versions of SQL are available. These include Sybase SQL Server, Microsoft SQL Server, IBM OS/2 Extended Edition Database Manager, DEC Rdb/VMS, and Oracle Server for OS/2 (Khoshafian et al.) for client/server systems, and XDB and SQLBase, as well as versions of R:Base and dBASE, for the personal computer.

The INGRES system was originally developed as a database management system with its own data language, QUEL, which like SQL is modeled on relational calculus. In the last few years, commercial INGRES has been expanded to support SQL as well as QLTEL. This is important since SQL has been adopted as the ANSI standard.

Relational database management systems support a wide variety of features in addition to their language capability. These features include security, integrity, high performance data access and update, and data dictionary or information schema control. Although the name SQL suggests that it is a ‘query’ language. It includes table definition, database update, view definition, and privilege granting. In addition to query facilities. In this chapter, we will study the table definition, query, update and view definition capabilities of SQL—in that order. Our coverage of SQL will include aspects of the 1992 ANSI standard, known as SQL-92. SQL-02 is a significant enhancement to the earlier versions of standard SQL.