(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

 

(i) The SAVEPOINT command is used to temporarily save a transaction so that you can rollback to the point whenever required.
(ii) The different states of our table can be saved at any time using different names and the rollback to that state can be done using the ROLLBACK command.
(iii) SAVEPOINT savepoint_name:
      UPDATE student SET Name = 'Mini' WHERE Admno=105;
      SAVEPOINT A;

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)

Constraint:
Constraints are used to limit the type of data that can go into a table. This ensures the accuracy and reliability of the data in the database. Constraints could be either on a column level or a table level. Constraint is a condition applicable on a field or set of fields.
Primary key constraint:
(i) This constraint declares a field as a Primary key which helps to uniquely identify a record.
(ii) It is similar to unique constraint except that only one field of a table can be set as primary key.
(iii) The primary key does not allow NULL values.