Mysql Alter Date Type is used to modify or change the Column datatype in a table.
Understand with Example
The Tutorial cover an example on 'Mysql Alter Date Type'.To understand this example we create a table 'userform' with required fieldname and datatype respectively.The table 'userform' has a ID as Primary Key.
Create a 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, `contact` bigint(20) default NULL, PRIMARY KEY (`ID`) ) |
Describe userform:
The Describe userform is used to describe the table field,Null,Key,Default etc.
| Describe userform; |
| +----------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +----------+--------------+------+-----+---------+----------------+ | ID | int(11) | NO | PRI | | auto_increment | | username | varchar(100) | YES | | | | | fname | varchar(100) | YES | | | | | email | varchar(100) | YES | | | | | contact | bigint(20) | YES | | | | |
Select the record from table "userform":
| +----+----------+---------+----------------------+---------+ | ID | username | fname | email | contact | +----+----------+---------+----------------------+---------+ | 1 | vineet | vineet | vineet@roseindia.net | 12345 | | 2 | sourabh | Sourabh | srbh@roseindia.net | 12345 | +----+----------+---------+----------------------+---------+ |
Query to Alter Table "userform":
The Query Alter is used to modify the Table "userform" and change the column datatype from "contact( bigint)" to contact(varchar(130).
alter table userform change contact contact varchar(130); |
| +----------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +----------+--------------+------+-----+---------+----------------+ | ID | int(11) | NO | PRI | | auto_increment | | username | varchar(100) | YES | | | | | fname | varchar(100) | YES | | | | | email | varchar(100) | YES | | | | | contact | varchar(130) | YES | | | | |
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