DDL used to define integrity constraints - Database

Discussion

• Nirja Shah   -Posted on 30 Oct 15
  DDL
  - Data Definition Language (DDL) statements are used to define the database structure or schema. Some examples:
  
  - CREATE - Is is used to create objects in the database
  - ALTER - It alters the structure of the database
  - DROP - It deletes object from the database
  - TRUNCATE - It removes all the records from a table, including all spaces allocated for the records are removed
  - COMMENT - It adds comment to the data dictionary
  - RENAME - It renames an object
  
  DML
  - Data Manipulation Language (DML) statements are used for managing data within schema objects. Some examples:
  
  - SELECT - It retrieves data from the a database
  - INSERT - It inserts data into a table
  - UPDATE - It updates existing data within a table
  - DELETE - It deletes all records from a table, the space for the records remain
  - MERGE - The UPSERT operation (insert or update)
  - CALL - It calls a PL/SQL or Java subprogram
  - EXPLAIN PLAN - It explains the access path to data
  - LOCK TABLE - It controls concurrency
  
  DCL
  - Data Control Language (DCL) statements. Some examples:
  
  - GRANT - It gives user's access privileges to database
  - REVOKE - It withdraw access privileges given with the GRANT command
  

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