1、删除一列mysql>altertable表名drop列名;2、添加一列2.1添加一列到表的最后mysql>altertable表名add列名columnspecificationsandconstraints;2.2添加一列到表的开始mysql>altertable表名add列名columnspecificationsandconstraintsfirst;2.3添加一列到某列之后mysql>altertable表名add列名columnspecificationsandconstraintsafter列名;