Data definition language
- 1. Data definition language. Ms. V.VENNILA MCA., M.Phil.., Assistant Professor Bon Secours College for Women, Thanjavur.
- 2. AGENDA: • INTRODUCTION • DATA DEFINATION LAMGUAGE • TYPES OF DDL AUTHORIZATION • DDL IN DATA MANIPULATION • DDL IN RELATIONAL DATABASE • CONCLUSION
- 3. INTRODUCTION • A collection of interrelated data and set of program to access the data. • To provide a way to store and retrieve database information • To keep information about all customers a saving accounts. • To allow users to manipulate the information. • File processing system.
- 4. DATA DEFINITION LANGUAGE • The database schema by set of definition expressed by a special language is called data definition language. • The storage structured and access methods used by the database system in DDL , is called data storage and definition language. • The output of the DDL list, placed in the data dictionary which contains meta data(data about data).
- 5. TYPES OF DDL AUTHORIZATION • There are four types of authorization in data definition language. READ AUTHORIZATION: allow only reading. INSERT AUTHORIZATION: allow only insertion of new data. UPDATE AUTHORIZATION: allow modification but not deletion. DELETE AUTHORIZATION: allow deletion of data.
- 6. DDL IN DATA MANIPULATION • Data manipulation language that enables users to access and manipulate data by the appropriate data model. • Data definition language allow one to define tables, integretity constrains, assertions etc. • There are many types of accesses in data manipulation language. • Data manipulation language is the mostly in the DDL concept. • SYNTAX: >create table account(accno char(10), balance integer);
- 7. DDL IN RELATIONAL DATABASE • Relational database uses a collection of tables to represent both data and relationships among those data. • There are four parts of the relational database, Tables Data manipulation language Data definition language Database access from application program
- 8. CONCLUSION • Data definition language is a standard for commands that define the different structures in a database • Data definition language statements create, modify, and remove database objects such as tables, indexes, and users. • Common data definition language statements are CREATE,ALTER, and DROP.