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Mysql Alter Column Default

                         

Mysql Alter Column Default is used to modify the table and add a default column to Null.

Understand with Example

The Tutorial illustrate an example from 'Mysql Alter Column Default'. To understand and grasp this example we create a table 'userform' with required fieldnames and datatypes respectively.The table 'userform' has a primary key ID column.

Create table "userform":

CREATE TABLE `userform` ( 
`ID` int(11) NOT NULL auto_increment, 
`username` varchar(100) default NULL, 
`fname` varchar(100) default NULL, 
`email` varchar(100) default NULL, 
`count` bigint(20) default NULL, 
PRIMARY KEY (`ID`) 

 

+----+----------+---------+----------------------+-------+
| ID | username | fname | email | count |
+----+----------+---------+----------------------+-------+
| 1 | vineet | vineet | vineet@roseindia.net | 0 |
| 2 | sourabh | Sourabh | srbh@roseindia.net | 0 |
+----+----------+---------+----------------------+-------+

Alter the table 'userform' and add column to set default:

The Query Alter is used to modify table 'usertable' and add the column default value to Null.

ALTER table usertable Modify last_name varchar(50) null;

Describe userform:

The Describe table is used to show the table  fieldname, Type, Null, Key, Default etc.

Describe usertable;

Output

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

                         

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