SQL Alter Column type
Alter Column type in SQL is used to change or recreate the data type of
existing column.
Understand with Example
The Tutorial brings you the simplest and easiest example, which helps
you to understand SQL Alter Column type. The Table 'Stu_Table' is created
with the help of create statement specifying its field attribute
and data type. The insert into statement add the records or rows to
the table. The Select statement return you the records added to the
table using insert into statement.
Create Table Stu_Table
create table Stu_Table(Stu_Id varchar(2), Stu_Name varchar(10),
Stu_Class varchar(10))
|
Insert data into Stu_Table
insert into Stu_Table (Stu_Id, Stu_Name) values(1,'Komal');
insert into Stu_Table (Stu_Id, Stu_Name) values(2,'Ajay');
insert into Stu_Table (Stu_Id, Stu_Name) values(3,'Rakesh');
insert into Stu_Table (Stu_Id, Stu_Name) values(4,'Bhanu');
insert into Stu_Table (Stu_Id, Stu_Name) values(5,'Santosh');
|
Stu_Table
+--------+----------+-----------+
| Stu_Id | Stu_Name | Stu_Class |
+--------+----------+-----------+
| 1 | Komal | 10 |
| 2 | Ajay | 10 |
| 3 | Rakesh | 10 |
| 4 | Bhanu | 10 |
| 5 | Santosh | 10 |
+--------+----------+-----------+
|
Describe Stu_Table
The Describe Stu_Table show you the field, data
type, null etc of the table 'Stu_Table'.
+-----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| Stu_Id | varchar(2) | YES | | | |
| Stu_Name | varchar(10) | YES | | | |
| Stu_Class | varchar(10) | YES | | | |
+-----------+-------------+------+-----+---------+-------+
|
Alter column type Query
The Alter Table alter the table 'stu_Table'
and MODIFY keywords modify the data type of Stu_Id(varchar (2))
into Stu_Id( int(3)).
ALTER TABLE Stu_Table MODIFY Stu_Id int(3)
|
Describe Stu_Table
When you see the structure of table using Describe
Stu_Table, the output is displayed as:
+-----------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+-------+
| Stu_Id | int(3) | YES | | | |
| Stu_Name | varchar(10) | YES | | | |
| Stu_Class | varchar(10) | YES | | | |
+-----------+--------------+------+-----+---------+-------+
|
|
Del.icio.us
Digg
Google
Spurl
Blink
Furl
Simpy
Y! MyWeb
