快速修改MySQL字段类型

方法： 直接从系统视图构造修改的sql

select 
concat('alter table '
       ,table_name
       ,' CHANGE '
       ,COLUMN_NAME, ' '
       ,COLUMN_NAME, ' '
       ,DATA_TYPE
       ,'('
       ,CHARACTER_MAXIMUM_LENGTH
       ,') CHARACTER SET utf8 COLLATE utf8_general_ci comment "'
       ,COLUMN_COMMENT
       ,'";'
      )
from information_schema.`COLUMNS` where TABLE_NAME='YOUR_TABLE'
and CHARACTER_SET_NAME = 'latin1'