SQL stands for Structured Query Language. and it is generally referred to as SEQUEL. SQL is simple language to learn. SQL is a Non-Procedural language, as compared to the procedural or third generation languages (3GLs) such as COBOL and C. SQL was developed by IBM in the 1970s.
The American National Standards Institute (ANSI) published its first SQL standard in 1986 and a second widely adopted standard in 1989. ANSI released updates in 1992, known as SQL92 and SQL2, and again in 1999, termed both SQL99 and SQL3. Each time, ANSI added new features and incorporated new commands and capabilities into the language.
SQL is a simple, yet powerful, language used to create, access, and manipulate data and structure in the database.
Why SQL?
- Allows users to access data in relational database management systems.
- Allows users to describe the data.
- Allows users to define the data in database and manipulate that data.
- Allows to embed within other languages using SQL modules, libraries & pre-compilers.
- Allows users to create and drop databases and tables.
- Allows users to create view, stored procedure, functions in a database.
- Allows users to set permissions on tables, procedures, and views
History
1970 -- Dr. Edgar F. "Ted" Codd of IBM is known as the father of relational databases. He described a relational model for databases.
1974 -- Structured Query Language appeared.
1978 -- IBM worked to develop Codd's ideas and released a product named System/R.
1986 -- IBM developed the first prototype of relational database and standardized by ANSI. The first relational database was released by Relational Software and its later becoming Oracle.
SQL Statements categories:
DDL - Data Definition Language.
DDL is used to define, alter, or drop database objects and their privileges. DDL statements will implicitly perform a commit.
DDL Statements:
Create - It is used to create objects(tables, views) in the database.
Alter - It is used to alter the structure of the database objects.
Drop - Delete database objects (It will invalidate the dependent objects ,it also drops indexes, triggers and referential integrity constraints ).
Truncate - remove all records from a table, including all spaces allocated for the records are removed (It is fast as compared to Delete and does not generate undo information as Delete does. It performs an implicit commit as it is a DDL. It resets the high water mark.)
Grant - 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 - Select data from the database
Insert - It is used to insert data into a table
Update - It is used to update existing data within a table
Delete - It removes rows from the table.
DCL - Data Control Language
Following are the examples of Data control Statements.
DCL Statements:
Commit - It will end the current transaction making the changes permanent and visible to all users..
Savepoint - It will identify a point(named SAVEPOINT) in a transaction to which you can later roll back
Rollback - It will undo all the changes made by the current transaction.
Set-Transaction - It is used to define the properties of a transaction.
The American National Standards Institute (ANSI) published its first SQL standard in 1986 and a second widely adopted standard in 1989. ANSI released updates in 1992, known as SQL92 and SQL2, and again in 1999, termed both SQL99 and SQL3. Each time, ANSI added new features and incorporated new commands and capabilities into the language.
SQL is a simple, yet powerful, language used to create, access, and manipulate data and structure in the database.
Why SQL?
- Allows users to access data in relational database management systems.
- Allows users to describe the data.
- Allows users to define the data in database and manipulate that data.
- Allows to embed within other languages using SQL modules, libraries & pre-compilers.
- Allows users to create and drop databases and tables.
- Allows users to create view, stored procedure, functions in a database.
- Allows users to set permissions on tables, procedures, and views
History
1970 -- Dr. Edgar F. "Ted" Codd of IBM is known as the father of relational databases. He described a relational model for databases.
1974 -- Structured Query Language appeared.
1978 -- IBM worked to develop Codd's ideas and released a product named System/R.
1986 -- IBM developed the first prototype of relational database and standardized by ANSI. The first relational database was released by Relational Software and its later becoming Oracle.
SQL Statements categories:
DDL - Data Definition Language.
DDL is used to define, alter, or drop database objects and their privileges. DDL statements will implicitly perform a commit.
DDL Statements:
Create - It is used to create objects(tables, views) in the database.
Alter - It is used to alter the structure of the database objects.
Drop - Delete database objects (It will invalidate the dependent objects ,it also drops indexes, triggers and referential integrity constraints ).
Truncate - remove all records from a table, including all spaces allocated for the records are removed (It is fast as compared to Delete and does not generate undo information as Delete does. It performs an implicit commit as it is a DDL. It resets the high water mark.)
Grant - 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 - Select data from the database
Insert - It is used to insert data into a table
Update - It is used to update existing data within a table
Delete - It removes rows from the table.
DCL - Data Control Language
Following are the examples of Data control Statements.
DCL Statements:
Commit - It will end the current transaction making the changes permanent and visible to all users..
Savepoint - It will identify a point(named SAVEPOINT) in a transaction to which you can later roll back
Rollback - It will undo all the changes made by the current transaction.
Set-Transaction - It is used to define the properties of a transaction.
