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

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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