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 | [email protected] | 0 | | 2 | sourabh | Sourabh | [email protected] | 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 | | | | +------------+--------------+------+-----+---------+-------+ |