1.两张表，店铺表（s_id，sname,loc）和订单表(o_id,oname,money,s_id)，店铺和订单是一对多关系，查询订单数大于等于20的店铺.
答：select s.s_id,s.sname from shop s inner join ordertable o on s.s_id = o.s_id group by s.s_id,s.sname having count(o.o_id)>=20;
2.给两张表t1和t2,t1有列id,name,t2有列id，name，log,t1表中id=10的name更新了，怎么把t1中id为10的那行name值更新到t2表中id为10的name中？（t1和t2的id有关联）
答：update t1,t2 set t2.name=t1.name where t1.id=t2.id and t1.id=10;
原文：https://www.cnblogs.com/hexiaoming/p/9107413.html