1.select * from zy where bj='1832';
2.select * from zy where bj='1833' and ywcj between 80 and 90;
3.select * from zy where id limit 4,6;
4.select id,xm from zy where bj=1832 and yycj=98 and sxcj=77;
5.select * from zy where bj=1832 order by ywcj desc;
6.select xm from zy where bj in(1832,1833) and ywcj<80 and sxcj<80;
7.select xm,bj from zy where ywcj is null;
8.select xm from zy where ywcj<60;
9.select avg(sxcj),bj from zy group by bj;
10.select sum(ywcj),bj from zy group by bj;
11.update zy set ywcj=60 where ywcj<60;
12.select xm,nl from zy where ywcj>70 and sxcj>70 and yycj>70;
13.select xm,bj from zy where yycj>70 and (sxcj>60 or ywcj>60);
14.select count(bj) from zy group by bj;
15.select bj,count(*) from zy where sxcj>80 group by bj;
16.select max(yycj),bj,xm from zy group by bj;
17.alter table zy add (xb int(4),dh bigint(20),dz varchar(20));
18.
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