Database language
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This document discusses database languages used in database management systems (DBMS). It describes three types of database languages: data definition language (DDL) used to define and modify the database schema; data manipulation language (DML) used to insert, update, delete and retrieve data; and data control language (DCL) used to control access privileges. Examples are provided for common statements in each language type like CREATE, ALTER, DROP for DDL and INSERT, UPDATE, DELETE, SELECT for DML. Case sensitivity and data types are also briefly covered.
Database language
- 2. #WHAT IS DATABASE MANAGEMENT SYSTEM?? A database management system (DBMS) is system software for creating and managing database. The DBMS provides users and programmers with a systematic way to create, retrieve, update and manage data. #There are many part of DBMS: • Introduction to Database Management System • DBMS vs File System • View of data • Data models • Database Languages. • Database users and administrators • Transaction Management • Database System Structure • Application architectures
- 3. # In DBMS has 3 types language: *Data Definition Language(DDL). *Data Manipulation Language(DML). *Data Control language (DCL). #Data Definition Language(DDL): • Database language that is used to create, delete or modify database schema is called DDL. • It is used by Database Administrators(DBA) to specify the conceptual schema. • DDL interpreter converts DDL statements into equivalent low level statements understood by the DBMS. • Normally, create, alter, and drop statements are DDL statements. • DDL statements make changes in the schema
- 4. Example: For alter command Alter table Student ADD COLUMN address varchar(20) ; Example: For drop command drop Student; Example: For create command create table Student ( sid number(4), sname varchar2s(50), DOB varchar2(15) );
- 5. *DATA MANIPULATION LANGUAGE(DML) • Database language that enables insert, update, delete, and retrieval of data from the database is called Data Manipulation Language. • DML complier converts DML statements into equivalent low level statements that the database understands. • Normally, insert, update, delete, select are DML commands. • DML reflects change in the instance, not the schema
- 6. Example: For insert Insert into Student values(“A-101”, “Ramesh”, 12); Example: for update Update Student Set class = 11 Where sid = “A-101” ; Example: for select Select * From Student Example: For delete Delete from student Where sname = “RAj”
- 7. •Data Control language (DCL): DCL statements control access to data and the database using statements such as GRANT and REVOKE. A privilege can either be granted to a User with the help of GRANT statement. The privileges assigned can be SELECT, ALTER, DELETE, EXECUTE, INSERT, INDEX etc. In addition to granting of privileges, you can also revoke (taken back) it by using REVOKE command.
- 9. *In SQL, cases are insensitive. So, instead of Student one can write StUdEnT as well. * Also, for integer values “12” is incorrect but 12 is correct. *And, for char and varchar “course” is correct and course is incorrect. Note that