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SQL language is the basic language to handle data in any application to communicate between database/server and front end. This SQL tutorial will give you detailed introduction about SQL language and all it’s concepts.
- Structured Query language is shortly called as SQL.
- We can access and manipulate all databases and tables using SQL.
- SQL is an ANSI and ISO standard.
- SQL is not case sensitive.
- SQL is a standard language for relational database management system (RDBMS).
- The relational database management system is nothing but a program that allows us to insert, update, select, delete records in the database system and administrates the database using SQL. Some of relational database management systems (RDBMS) are Oracle, DB2, SQL server, MYSQL, Microsoft Access, etc.
- SQL itself is not a database, whereas, it is just a language that is used to create databases, tables and to manipulate the data in the servers (e.g. SQL server, Oracle etc.)
- SQL can perform many operations in a database and server. Few of them are given below. Please refer the whole SQL tutorial for all the operations that a SQL can perform.
- SQL can fetch the data from the database. Also, it can insert, delete and update records in a database. SQL can create tables in a database and SQL can create databases in the server.
SQL language is also extended as T-SQL and PL/SQL:
- T-SQL (Transaction SQL) is an extension to the SQL which is used especially by MS SQL server, Microsoft and Sybase RDBMS. T-SQL has many advance features like procedural programming, local variables and many data processing functions.
- PL/SQL (procedural language/SQL) is also an extension of SQL which is has advanced functionality than SQL and it is available in Oracle database and IBM’s DB2 database.
What is a database?
A database is an application which is used to store and retrieve the data. All the data are stored in the database objects called tables.
What is a table?
Table is a database object which actually stores the collection of related data. It consists of rows and columns.
What is a server?
A physical computer or a computer program that acts as a centralized resource for other computers in a network is called a server. A server serves all the computers which are connected in a network.
SQL language is divided into 3 major aspects:
- Data Definition Language – DDL
- Data Manipulation Language –DML
- Data control language – DCL
1. SQL language – Data Definition Language (DDL):
- Data definition language is also referred as DDL that often deals with description and schemas of the database/table, i.e. How a data should reside in a database.
- Create, drop, alter, truncate, comment, rename are some of the SQL functions those actually define the schema and the definition of the objects that stores the data.
2. SQL language – Data Manipulation Language (DML):
Data Manipulation Language is also referred as DML that often deals with the actual data stored in the database objects.
Select, insert into, update, delete statements are some examples for DML that handles and operates on the actual data in the database/table.
3. SQL language – Data control Language (DCL):
Data Control Language is also referred as DCL which manages access to the objects in the database/server and other controls. SQL commands such as GRANT, REVOKE are some examples of data control commands.
REFERENCE E-BOOKS & RESEARCH PAPERS:
- SQL language- Don Chamberlin, IBM Almaden Research Ce