1)
ALTER TABLE EMPLOYEE ADD SSN INT;
Query OK, 0 rows affected (0.81 sec)
Records: 0  Duplicates: 0  Warnings: 0

desc EMPLOYEE;
+------------+-------------+------+-----+---------+-------+
| Field      | Type        | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+-------+
| emp_id     | int(11)     | NO   | PRI | NULL    |       |
| Name       | varchar(30) | NO   |     | NULL    |       |
| City       | varchar(40) | YES  |     | NULL    |       |
| DOB        | date        | YES  |     | NULL    |       |
| aadhaar_no | int(11)     | NO   |     | NULL    |       |
| SSN        | int(11)     | YES  |     | NULL    |       |
+------------+-------------+------+-----+---------+-------+
6 rows in set (0.00 sec)


2)
ALTER TABLE EMPLOYEE MODIFY COLUMN DOB YEAR;
Query OK, 0 rows affected (1.32 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> DESC EMPLOYEE;
+------------+-------------+------+-----+---------+-------+
| Field      | Type        | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+-------+
| emp_id     | int(11)     | NO   | PRI | NULL    |       |
| Name       | varchar(30) | NO   |     | NULL    |       |
| City       | varchar(40) | YES  |     | NULL    |       |
| DOB        | year(4)     | YES  |     | NULL    |       |
| aadhaar_no | int(11)     | NO   |     | NULL    |       |
| SSN        | int(11)     | YES  |     | NULL    |       |
+------------+-------------+------+-----+---------+-------+
6 rows in set (0.00 sec)



3)
ALTER TABLE EMPLOYEE DROP emp_id;
Query OK, 0 rows affected (0.83 sec)
Records: 0  Duplicates: 0  Warnings: 0



mysql> DESC EMPLOYEE;
+------------+-------------+------+-----+---------+-------+
| Field      | Type        | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+-------+
| Name       | varchar(30) | NO   |     | NULL    |       |
| City       | varchar(40) | YES  |     | NULL    |       |
| DOB        | year(4)     | YES  |     | NULL    |       |
| aadhaar_no | int(11)     | NO   |     | NULL    |       |
| SSN        | int(11)     | YES  |     | NULL    |       |
+------------+-------------+------+-----+---------+-------+
5 rows in set (0.00 sec)



4)
ALTER TABLE EMPLOYEE ADD CONSTRAINT c1 UNIQUE(SSN,aadhaar_no);
Query OK, 0 rows affected (0.29 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> DESC EMPLOYEE;
+------------+-------------+------+-----+---------+-------+
| Field      | Type        | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+-------+
| Name       | varchar(30) | NO   |     | NULL    |       |
| City       | varchar(40) | YES  |     | NULL    |       |
| DOB        | year(4)     | YES  |     | NULL    |       |
| aadhaar_no | int(11)     | NO   |     | NULL    |       |
| SSN        | int(11)     | YES  | MUL | NULL    |       |
+------------+-------------+------+-----+---------+-------+
5 rows in set (0.00 sec)




6)

ALTER TABLE EMPLOYEE RENAME TO PERSON;
Query OK, 0 rows affected (0.15 sec)




7)