Home Sql Mysql-example Mysql Alter Allow Null

Related Tutorials


 
 

Share on Google+Share on Google+

Mysql Alter Allow Null

Advertisement
Mysql Alter Allow Null is used to change the Null Type of a column in a table.The Allow Null allows the null type characteristics in a column of the table.

Mysql Alter Allow Null

     

Mysql Alter Allow Null is used to change the Null Type of a column in a table.The Allow Null allows the null type characteristics in a column of the table. The Null Type column can be leave empty.

Understand with Example

The section of Tutorial illustrate an example from 'Mysql Alter Allow Null'.To understand this example we create a table 'usertable' with required fieldname and datatype respectively.

 

 

 

Create table 'usertable':

CREATE TABLE `usertable` ( 
`username` varchar(200) NOT NULL, 
`first_name` varchar(200) NOT NULL, 
`last_name` varchar(200) NOT NULL 
)

Query to insert records or rows to the table 'usertable':

The insert into is used to add the records or rows to the table 'usertable'.


insert into usertable values('vin','Vineet','Bansal');
insert into usertable values(' srbh','Sourabh','Ranjan');
insert into usertable values(' amit','Amit','Kumar');

insert into usertable values('sandeep','Sandeep','Kumar');

Query to view the details of 'usertable':

The Select Query helps you to return the detail from table 'usertable'.

select * from usertable;

 

+----------+------------+-----------+
| username | first_name | last_name |
+----------+------------+-----------+
| vin | Vineet | Bansal |
| srbh | Sourabh | Ranjan |
| amit | Amit | Kumar |
| sandeep | Sandeep | Kumar |

Alter Table "usertable" last_name allow NULL

The Alter Query is used to modify or change the 'usertable ' definition and modify keyword allows the null value to be 'YES' in the table 'usertable'.

ALTER table usertable Modify last_name varchar(50) null;

Describe Table:

The Describe Table is used to describe the FieldType,Null,Key,etc of table 'usertable'..

Describe usertable;

 

+------------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------+--------------+------+-----+---------+-------+
| username | varchar(50) | NO | | | |
| first_name | varchar(200) | NO | | | |
| last_name | varchar(50) | YES | | | |
+------------+--------------+------+-----+---------+-------+
Advertisement

If you enjoyed this post then why not add us on Google+? Add us to your Circles



Liked it!  Share this Tutorial


Follow us on Twitter, or add us on Facebook or Google Plus to keep you updated with the recent trends of Java and other open source platforms.

Posted on: January 17, 2009

Related Tutorials

Discuss: Mysql Alter Allow Null  

Post your Comment


Your Name (*) :
Your Email :
Subject (*):
Your Comment (*):
  Reload Image
 
 
Comments:0
DMCA.com