Changing a Column Type : Alter Column « Table « MySQL Tutorial

1. MySQL Tutorial
2. Table
3. Alter Column

mysql>
mysql>
mysql> CREATE TABLE Employee(
    ->     id            int,
    ->     first_name    VARCHAR(15),
    ->     last_name     CHAR(15),
    ->     start_date    DATE,
    ->     end_date      DATE,
    ->     salary        FLOAT(8,2),
    ->     city          VARCHAR(10),
    ->     description   VARCHAR(15)
    -> );
Query OK, 0 rows affected (0.02 sec)

mysql>
mysql> DESCRIBE employee;
+-------------+-------------+------+-----+---------+-------+
| Field       | Type        | Null | Key | Default | Extra |
+-------------+-------------+------+-----+---------+-------+
| id          | int(11)     | YES  |     | NULL    |       |
| first_name  | varchar(15) | YES  |     | NULL    |       |
| last_name   | char(15)    | YES  |     | NULL    |       |
| start_date  | date        | YES  |     | NULL    |       |
| end_date    | date        | YES  |     | NULL    |       |
| salary      | float(8,2)  | YES  |     | NULL    |       |
| city        | varchar(10) | YES  |     | NULL    |       |
| description | varchar(15) | YES  |     | NULL    |       |
+-------------+-------------+------+-----+---------+-------+
8 rows in set (0.00 sec)

mysql>
mysql>
mysql> ALTER TABLE employee
    -> CHANGE Last_Name Last_Name VARCHAR(50);
Query OK, 0 rows affected (0.05 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql>
mysql> DESCRIBE employee;
+-------------+-------------+------+-----+---------+-------+
| Field       | Type        | Null | Key | Default | Extra |
+-------------+-------------+------+-----+---------+-------+
| id          | int(11)     | YES  |     | NULL    |       |
| first_name  | varchar(15) | YES  |     | NULL    |       |
| Last_Name   | varchar(50) | YES  |     | NULL    |       |
| start_date  | date        | YES  |     | NULL    |       |
| end_date    | date        | YES  |     | NULL    |       |
| salary      | float(8,2)  | YES  |     | NULL    |       |
| city        | varchar(10) | YES  |     | NULL    |       |
| description | varchar(15) | YES  |     | NULL    |       |
+-------------+-------------+------+-----+---------+-------+
8 rows in set (0.02 sec)

mysql>
mysql>
mysql> drop table Employee;
Query OK, 0 rows affected (0.00 sec)

mysql>