Can we use ADD and CHANGE with ALTER Statement in MySQL?


Yes, we can use ADD and CHANGE with ALTER statement. Let us first create a table −

mysql> create table DemoTable
   -> (
   -> Name varchar(100),
   -> Age int
   -> );
Query OK, 0 rows affected (0.84 sec)

Now check the description of table.

mysql> desc DemoTable;

This will produce the following output −

+-------+--------------+------+-----+---------+-------+
| Field | Type         | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| Name  | varchar(100) | YES  | | NULL |   |
| Age   | int(11)      | YES | | NULL    | |
+-------+--------------+------+-----+---------+-------+
2 rows in set (0.25 sec)

Here is the query with ALTER to update a column name as well adding new columns −

mysql> alter table DemoTable
-> add column Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
-> add column CountryName varchar(100) after Age,
-> change column Name FirstName varchar(200);
Query OK, 0 rows affected (1.51 sec)
Records: 0  Duplicates: 0  Warnings: 0

Now check the description of table once again −

mysql> desc DemoTable;

This will produce the following output −

+-------------+--------------+------+-----+---------+----------------+
| Field       | Type         | Null | Key | Default | Extra          |
+-------------+--------------+------+-----+---------+----------------+
| FirstName   | varchar(200) | YES  |     | NULL    |                |
| Age         | int(11)      | YES  |     | NULL    |                |
| CountryName | varchar(100) | YES  |     | NULL    |                |
| Id          | int(11)      | NO   | PRI | NULL    | auto_increment |
+-------------+--------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)
raja
Published on 11-Jul-2019 12:47:06
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