更新数据
update custmers set cust_city=replace(cust_city,'市','city') where cust_id > 1000; update customer set cust_adderess = '新福路12号',cust_city='厦门市' where cust_id=1; update customers set cust_city='珠海' where cust_id<5;
删除数据
delete from customers where cust_id where cust_id between 200 and 300;
更新和删除数据的指导原理