Data: Raw fact or information which has real existence is known as Data.
Data Base: Collection of data or information in a particular area is known as database.
DBMS: All the data or information that is sequentially stored in DB and which can be retrieved from DB in according to the requirement of the user is known as Data Base Management System.
DBA: Data Base Administrator will control all the database transaction in the Data Base Management System.
SQL: SQL is a database computer language designed for the retrieval and management of data in a relational database.
DDL(Data Definition Language): DDL or Data Definition Language actually consists of the SQL commands that can be used to define the database schema. It simply deals with descriptions of the database schema and is used to create and modify the structure of database objects in the database.
Examples of DDL commands:
CREATE – is used to create the database or its objects (like table, index, function, views, store procedure and triggers).
DROP – is used to delete objects from the database.
ALTER-is used to alter the structure of the database.
TRUNCATE–is used to remove all records from a table, including all spaces allocated for the records are removed.
COMMENT –is used to add comments to the data dictionary.
RENAME –is used to rename an object existing in the database.
DML(Data Manipulation Language): The SQL commands that deals with the manipulation of data present in the database belong to DML or Data Manipulation Language and this includes most of the SQL statements.
Examples of DML:
SELECT – is used to retrieve data from the database.
INSERT – is used to insert data into a table.
UPDATE – is used to update existing data within a table.
DELETE – is used to delete records from a database table.
DCL(Data Control Language): DCL includes commands such as GRANT and REVOKE which mainly deals with the rights, permissions and other controls of the database system.
Examples of DCL commands:
GRANT-gives user’s access privileges to the database.
REVOKE-withdraw user’s access privileges given by using the GRANT command.
TCL(TransactionControl Language): TCL commands deals with the transaction within the database.
Examples of TCL commands:
COMMIT– commits a Transaction.
ROLLBACK– rollbacks a transaction in case of an error occurs.
SAVEPOINT–sets a savepoint within a transaction.
SET TRANSACTION–specify characteristics for the transaction.
Data Independence: A Database system normally contains a lot of data in addition to user data. It is rather difficult to modify or update a set of metadata once it is stored in the database. so that when we change data at one layer, it does not affect the data at another level. This data is independent but mapped to the physical level and logical level.
Physical data independence: the actual data is stored in the form of bits in the hard disk. Physical data independence is used to change the physical data without effecting logical data.
Logical data independence: It is a data about the database, it stores information about how the data is managed.
I hope this article is useful to you, plz follow the next volume for more information.
You can write to me at codingallrounders@gmail.com
please post your doubts in the comment box.
Subscribe by Email
Follow Updates Articles from This Blog via Email
No Comments