Transactional Control Language (TCL) commands are used to manage transactions in the database. These are used to manage the changes made to the data in a table by DML statements.

To create a database, type the following command in the prompt:
CREATE DATABASE database_name;
For example; To create a database to store the tables:
CREATE DATABASE stud;
(ii) To work with the database, type the following command.
USE DATABASE;
For example ; To use the stud database created, give the command USE stud;

RDBMS is a type of DBMS with a row-based table structure that connects related data elements and includes functions related to Create, Read, Update and Delete operations, collectively known as CRUD.

(i) It should identify the type of data division such as data item, segment, record and database file.
(ii) It gives a unique name to each data item type, record type, file type and data base.
(iii) It should specify the proper data type.
(iv) It should define the size of the data item.
(v) It may define the range of values that a data item may use.
(vi) It may specify privacy locks for preventing unauthorized data entry.

(i) Unique Constraint
(ii) Primary Key Constraint
(iii) Default Constraint
(iv) Check Constraint

(i) The DISTINCT keyword is used along with the SELECT command to eliminate duplicate rows in the table. This helps to eliminate redundant data.

(ii) For Example: SELECT DISTINCT Place FROM Student;
    Will display the following data as follows:
    Place
    Chennai
    Banglore
    Delhi

 

Data Definition Language:
(i) Create Command: To create tables in the database.
CREATE TABLE Student
(Admno integer,
      Name char(20),
      Gender char(1),
      Age integer,
      Place char(10),
);
(ii) Alter Command: The ALTER command is used to alter the table structure like adding a column, renaming the existing column, change the data type of any column or size of the column or delete the column from the table.
ALTER TABLE <table-name> ADD <column-name><data type><size>;
To add a new column "Address" of type 'char' to the Student table, the command is used as
ALTER TABLE Student ADD Address char;
(iii) Drop Command: The DROP TABLE command is used to remove a table from the database.
The table can be deleted by DROP TABLE command in the following way:
DROP TABLE table-name;

ALTER TABLE <table-name> ADD <column- name><data type><size>;
Example: ALTER TABLE Student MODIFY Address char (25)

TCL commands:
(i) COMMIT command: The COMMIT command is used to permanently save any transaction to the database. When any DML commands like INSERT. UPDATE. DELETE commands are used. the changes made by these commands are not permanent. It is marked permanent only after the COMMIT command is given from the SQL prompt. Once the COMMIT command is given. the changes made cannot be rolled back. The COMMIT command is used as COMMIT;
(ii) ROLLBACK command:
The ROLLBACK command restores the database to the last committed. state. It is used with SAVEPOINT command to jump to a particular savepoint location. The syntax for the ROLLBACK command is: ROLLBACK TO save point name;
(iii) SAVEPOINT command:
The SAVEPOINT command is used to temporarily save a transaction so that you can rollback to the point whenever required. The different states of our table can be saved at anytime using different names and the rollback to that state can be done using the ROLLBACK command.
SAVEPOINT savepoint_name;

ALTER Command:
(i) The ALTER command is used to alter the table structure like adding a column, renaming the existing column, change the data type of any column or size of the column or delete the column from the table. It is used in the following way:
(ii) ALTER TABLE <table-name>  ADD  <column-name><data type> <size>;
(iii) To add a new column "Address" of type 'char' to the Student table, the command is used as
(iv) ALTER TABLE Student ADD Address char;
To modify, existing column of table, the ALTER TABLE command can be used with MODIFY clause like wise:
(v) ALTER < table-name > MODIFY < column-name > < data type > < size >;
ALTER TABLE Student MODIFY Address char (25);
(vi) The above command will modify the address column of the Student table to now hold 25 characters.
(vii) The ALTER command can be used to rename an existing column in the following way:
(viii) ALTER < table-name > RENAME old-column- name TO new-column-name;
(ix) For example to rename the column Address to City, the command is used as :
(x) ALTER TABLE Student RENAME Address TO City;
(xi) The ALTER command can also be used to remove a column or all columns. for example to remove a particular column, the DROP COLUMN is used with the ALTER TABLE to remove a particular field, the command can be used as:
ALTER < table-name > DROP COLUMN < column-name >;
(xii) To remove the column City from the Student table, the command is used as :
ALTER TABLE Student DROP COLUMN City;

1. SELECT * FROM student WHERE gender = Male GROUP BY gender;
2. SELECT * FROM student WHERE Age > 18 ORDER BY DESC;

SQL commands are divided into five categories:

Data Definition Language:
(i) The Data Definition Language (DDL) consist of SQL statements used to define the database structure or schema.
(ii) It simply deals with descriptions of the database schema and is used to create and modify the structure of database objects in databases.
(iii) The DDL provides a set of definitions to specify the storage structure and access methods used by the database system.
DDL performs the following functions:
(i) It should identify the type of data division such as data item, segment, record and database file.
(ii) It gives a unique name to each data item type, record type, file type and data base.
(iii) It should specify the proper data type.
(iv) It should define the size of the data item.
(v) It may define the range of values that a data item may use.
(vi) It may specify privacy locks for preventing unauthorized data entry.
Commands:

Data Manipulation Language:
This is a computer programming language used for adding, removing and modifying data in a database. This language comprises the SQL-data change statements, which modify stored data but not the schema of the database table
Data Manipulation includes
(i) Insertion of new information into the database
(ii) Retrieval of information stored in a database
(iii) Deletion of information from the database.
(iv) Modification of data stored in the database
The DML is basically of two types:
Procedural DML - Requires a user to specify what data is needed and how to get it.
Non-Procedural DML - Requires a user to specify what data is needed without Specifying how to get it.
Commands:

Data Control Language:
(i) A Data Control Language (DCL) is a programming language used to control the access of data stored in a database. It is used for controlling privileges in the database (Authorization).
(ii) The privileges are required for performing all the database operations such as creating sequences, views of tables etc.
Commands:

Transactional Control Language:
Transactional control language (TCL) commands are used to manage transactions in the database. These are used to manage the changes made to the data in a table by DML statements.
Commands:

Data query language:
The Data Query Language consist of commands used to query or retrieve data from a database. One such SQL command in Data Query Language is