update tablename set name='newname' where age='oldname';
例子:将users表中姓名为‘张三’的人的姓名改为李四
update users set name='张三' where name='李四'
update tablename set name='newname' where age='oldname';
例子:将users表中姓名为‘张三’的人的姓名改为李四
update users set name='张三' where name='李四'