Modify the type and length of fields in MySQL

The commands for MySQL to modify field types are:

　　Mysql> ALTER TABLE name modify column field name type;

Suppose that there is a table in MySQL: Address, which has a field in the initial case of varchar (30), then the modified type char can be entered in the MySQL console:

　　ALTER TABLE address modify column City char (30);

Note the modification type should be cautious, because data between types needs to be converted, which can result in data errors or missing

If you want to extend the varchar (30) length, you can use:

　　ALTER TABLE address modify column city varchar (60);

The same type of data field increases the length is not a problem, is often used, but the reduction of length may result in data loss

Modify the type and length of fields in MySQL