What is sql?, Database Management System

Assignment Help:

What Is Sql?

 Structured Query Language (SQL) is a standard query language. It is usually used with all relational databases for data manipulation and definition.

All the relational systems support SQL, therefore allowing migration of database from one DBMS to a different. In fact, this is one of the reasons of the main success of Relational DBMS. A user may be capable to write a program using SQL for an application that includes data being stored in more than one DBMSs, given these DBMS support standard SQL. This feature is usually referred to as portability. Though, not all the features of SQL executed in one RDBMS are available in others because of customization of SQL. Though, please note there is just ONE standard SQL.

SQL gives an interface where the user can state "What" are the expected results. The query implementation plan and optimisation is performed by the DBMS. The query plan and optimisation shows how a query needs to be implemented. For instance, if three tables X, Y and Z are to be joined mutually then which plan (X JOIN Y) and then Z or X JOIN (Y JOIN Z) may be implemented. All these decisions are depend on statistics of the relations.

SQL is known as a non-procedural language as it just states what is to be dome rather than how it is to be complete. Also, as SQL is a higher-level query language, it is closer to a language like English. Thus, it is very user friendly.

The American National Standard Institute (ANSI) has designed standard versions of SQL. The first standard in this series was formed in 1986. It was known as a SQL-86 or SQL1. This standard was revised and better later and SQL-92 or SQL-2 was released. A newer standard of SQL is SQL3 which is also called as SQL- 99. In this part we will try to cover features from latest standards. Though, some features may be found to be very specific to definite DBMS.

Some of the main features of SQL are:

  • It is an English-like language.
  • It is a non procedural language.
  • It can process a one record as well as sets of records at a time.
  • It is dissimilar from a third generation language (C& COBOL). All SQL

Statements describe what is to be complete rather than how it is to be complete.

  • SQL is a data sub-language having of three built-in languages: Data definition language (DDL), Data manipulation language (DML) and Data control language (DCL).
  • It insulates the user from the underlying algorithm and structure.
  • SQL has facilities for defining database security, views, integrity constraints, transaction controls, etc.

Related Discussions:- What is sql?

What is the use of group by clause, What is the use of group by clause? ...

What is the use of group by clause? Group by clause is used to be relevant aggregate functions to a set of tuples. The attributes given in the group by clause are used to shape

What are the advantages of using a dbms, What are the advantages of using a...

What are the advantages of using a DBMS? The benefits of using a DBMS are a) Controlling redundancy b) Restricting unauthorized access c) Giving multiple user interfac

Entity relationship, how to write tables and drow E-R diagrams for hosiptal...

how to write tables and drow E-R diagrams for hosiptal management system and how to normalize and cardinalities?

01a_ImportCasting.xlsx, 01a_Broadway_LastFirst_yyyy-mm-dd Capstone Exercise...

01a_Broadway_LastFirst_yyyy-mm-dd Capstone Exercises You work as a production assistant in the office of the Green Man Theatre. One of your duties is to maintain the company datab

Mention the various user privileges, Mention the various user privileges ...

Mention the various user privileges All privileges directly granted to the user or role. All privileges granted to roles that have been granted to the user or role.

Project, Preliminary entities and attributes of human resourse management d...

Preliminary entities and attributes of human resourse management database management system

The file based system in dbms, The File Based System File based systems...

The File Based System File based systems are an early attempt to computerise the manual filing system. For example, a manual file can be set up to hold all the correspondence r

Central database schema, Consider an information system designed for an onl...

Consider an information system designed for an online company which provides IT products and services. These include desktops, laptops, networking products, IT books, parts, and te

Dml precompiler in database management system, DML Precompiler All th...

DML Precompiler All the DBMS have two basic sets of Languages - Data Definition Language (DDL) that have the set of commands needed to define the format of the data that is b

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd