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Brief Overview Of SQL

SQL full form for Structured Query Language and it is usually referred to as SEQUEL. SQL is effortless language to learn. SQL is a Nonprocedural language, in contrast to the procedural or third generation languages (3GLs) such as COBOL and C. SQL language is framed by IBM in the 1970s.
The American National Standards Institute (ANSI)printed  its initial SQL standard in 1986 and a subsequent extensively accepted standard in 1989. ANSI again proposed and released updates in 1992, known as SQL92 and SQL2, and again in 1999, termed both SQL99 and SQL3. Each time, ANSI added fresh features and included new commands and potential into the language.SQL is a simple, yet powerful, language used to create, access, and manipulate data and structure in the database.

overview of SQl


SQL commands  are grouped as the following categories:

DDL - Data Definition Language.
DDL is used to define, alter, or drop database objects and their privileges. DDL commands will perfectly perform a commit.
Here are the DDL commands:
  • Create:      This command is used to create objects(tables, views) in the database.
  • Alter:        This command is used to alter the structure of the database objects.
  • Drop:        This command is used to delete database objects
  • Truncate: This command is used to remove all records from a table, including all spaces allocated for the records are removed
  • Grant:       This command is used for assigning privileges

DML - Data Manipulation Language.
DML is used to access, create, modify or delete data in the structures of the database.
DML Statements:
  • Select:   This command is used to select data from the database
  • Insert:    This command is used to insert data into a table
  • Update:  This command is used to update existing data within a table
  • Delete:   This command is used to remove rows from the table.

DCL - Data Control Language
DCL is used to control all the actions performed on the database.
DCL Statements:
  • Commit:      This command will end the current transaction making the changes eternal and visible to all users.
  • Savepoint:   This Command will identify a point(named SAVEPOINT) in a transaction to which you can later roll back
  • Rollback:     This command will undo all the changes made by the current transaction.
  • Set- Transaction: This Command is used to define the properties of a transaction.

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