What is sql?, Database Management System

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.
Posted Date: 3/8/2013 6:20:23 AM | Location : United States







Related Discussions:- What is sql?, Assignment Help, Ask Question on What is sql?, Get Answer, Expert's Help, What is sql? Discussions

Write discussion on What is sql?
Your posts are moderated
Related Questions
Retrieve the S&S In-Chapter Database (in Microsoft Access format) from the text's Web site (or create the tables in Table 4-5 in a relational DBMS product). Write queries to answer

Explain the Functional Mode with help of an example. Functional Model  The functional model shows a computation and functional derivation of data values in it without ind

What are called jukebox systems? Jukebox systems have a few drives and numerous disks that can be loaded into single of the drives automatically.

What are the various properties of Relational tables? Relational tables have 6 properties: 1. Each row is unique. 2. Column values are of the same kind. 3. Values are

Define a job scheduling strategy that will meet business requirement of reporting availability by 6am CST for the following cubes? Show the job scheduling dependencies in a pictori

Briefly describe the different kinds of users of a DBMS.  Ans: Different sorts of DBMS users are: (a)  Software Engineers: These are the people accountable for developing ap

Describe the iterative and incremental life cycle For an iterative and incremental life cycle, two criteria are process and time. The main components of showing a project devel

Security And Integrity After Reading the concepts of database recovery in the last section, let us now deal with a vital concept that helps in minimizing consistency errors in

Explain Hierarchical Model ? Hierarchical Model - It was established to model several kinds of hierarchical organizations which exist in the real world. It uses tree structur

Question: (a) Can a set of data requirements be correctly modelled by two or more different ER diagrams? Explain your answer. You may use a small example, if you think it will