Mysql Alter Column Size
Mysql Alter Column Size is used to change the data size of a column in a
table.
Understand with Example
The Tutorial illustrate an example from 'Mysql Alter Column Size'. To
understand example we create table 'employees' that include empid as primary
key.
Query to create table:-
CREATE TABLE `employees` (
->Empid int(10),
->Empname varchar(60),
->date date
->PRIMARY KEY(empid)
->);
|
Query to insert data into Table named employees:
The insert into add the records or rows to the table 'employees'.
mysql>insert into employees values(01,'Girish','2008-12-22');
Query OK, 1 row affected (0.02 sec)
mysql>insert into employee1 values(02,'Komal','2008-12-23');
Query OK, 1 row affected (0.02 sec)
|
Query to view data of Table named employees:
To view the detail from table 'employee' we use select Query
that return the records from table 'employees'.
mysql> select * from employees;
|
Output:
+-------+---------+------------+
| Empid | Empname | date |
+-------+---------+------------+
| 1 | Girish | 2008-12-22 |
| 2 | Komal | 2008-12-23 |
+-------+---------+------------+
2 rows in set (0.00 sec)
|
Data type of Table named employees before altering column size:
The Query below define the table field ,data type,Null ,key ,default
etc properties.
+---------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+----------------+
| empid | int(11) | NO | PRI | NULL | auto_increment |
| Empname | varchar(60) | NO | | | |
| date | date | YES | | NULL | |
+---------+-------------+------+-----+---------+----------------+
3 rows in set (0.02 sec)
|
Query to alter column size of the Table named employees:
The Query Alter is used to modify the definition of table 'employees'
and change the size of column datatype.
mysql> alter table employees
-> change empname empname varchar(130);
Query OK, 2 rows affected (0.13 sec)
Records: 2 Duplicates: 0 Warnings: 0
|
Data type of Table named employees after altering column size:-
mysql> describe employees;
+---------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------+--------------+------+-----+---------+----------------+
| empid | int(11) | NO | PRI | NULL | auto_increment |
| empname | varchar(130) | YES | | NULL | |
| date | date | YES | | NULL | |
+---------+--------------+------+-----+---------+----------------+
3 rows in set (0.03 sec)
|
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