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
What is Index? An index is a physical structure having pointers to the data. Indices are created in an existing table to locate rows more quickly and efficiently. It is possibl

What is Outer join?  They can be employed while we want to keep all the tuples in R, or all those in S or all those in both relations in the result of the JOIN in spite of of w

Describe the different RAID levels.  Discuss the choices of the different RAID levels for different applications.          Ans:   There are several combinations of these approa

Define the phases of two phase locking protocol Growing phase: a transaction may get locks but not release any lock. Shrinking phase: a transaction might be release locks bu

how can apply joins on table

What is data block? Data Block - In oracle the data blocks are referred to as tablespaces. A tablespace is an fields of disk consisting of one or more disk files. A tablespace

Data Fragmentation "Fragmentation includes decomposing the data in relation to non-overlapping component relations". Why do we require fragmenting a relation?

What is meant by the degree of relationship set? The degree of relationship type is the number of participating entity types.

Explain the Weak Entity Set An Entity set which does not have sufficient attribute to make a primay key is known as weak entity set. For instance, dependents of an employee in

Define value set? Value set: It is a set of values. You do not always need a user to enter junk free text within all the fields. Therefore, Oracle Apps uses value set to valida