MySQL 之多表查询

练习题 1 ：

首先，第一步我们需要想创建库，和表格，并且把数据填写进去

use db_test;
create table product(
pid int,
pname varchar(50),
pprice int
)insert into product values(1,'手机',2300);
insert into product values(2,'电脑',5600);
insert into product values(3,'照相机',1200);
insert into product values(4,'投影仪',2500);create table user(
uid int,
uname varchar(50),
uage int,
usex varchar(20)
)
insert into user values(1,'李三',20,'男');
insert into user values(2,'张四',23,'男');
insert into user values(3,'赵五',25,'男');
insert into user values(4,'孙六',18,'男');
insert into user values(5,'孙悟空',24,'男');create table orderr(
opid int,
ouid int,
onumber varchar(50)
)insert into orderr values(1,1,123123);
insert into orderr values(1,2,112233);
insert into orderr values(2,1,234567);
insert into orderr values(2,5,787878);
insert into orderr values(3,4,343421);
insert into orderr values(3,5,909090);
insert into orderr values(4,2,212112);
insert into orderr values(4,1,343421);-- 1. 查询姓孙的用户的个数select count(*) from user where uname like '孙%';-- 2.查询年纪最大的两个用户名select uname from user ORDER BY uage desc limit 0,2;-- 3.查询李三买的商品名select product.pname from user INNER JOIN orderr on user.uid = orderr.ouid INNER JOIN product on orderr.opid = product.pid where uname = '李三';-- 4.查询购买过电脑的用户名select u.uname from product p,user u,orderr o where p.pid=o.opid and o.ouid = u.uid and pname='电脑';-- 5.查询订单是909090对应的用户名和商品名select u.uname,p.pname from product p,user u,orderr o where o.ouid = u.uid and o.opid = p.pid and onumber = '909090';-- 6.查询商品表中的最高价格的前两条数据select * from product ORDER BY pprice desc limit 0,2;

练习题2：

同样，第一步我们需要想创建库，和表格，并且把数据填写进去

练习题目操作：

use db_test;
create table s(
sno int,
sname varchar(50),
age int,
sex varchar(20)
)insert into s values(1,'张三',18,'男');
insert into s values(2,'李四',18,'女');
insert into s values(3,'王五',18,'男');
insert into s values(4,'赵六',18,'女');create table sc(
sno int,
cno int,
scgrade int
)insert into sc values(1,1,50);
insert into sc values(2,1,66);
insert into sc values(3,1,90);
insert into sc values(1,2,55);
insert into sc values(2,2,68);
insert into sc values(3,2,61);
insert into sc values(4,2,44);
insert into sc values(1,3,90);
insert into sc values(2,3,78);
insert into sc values(3,3,22);
insert into sc values(4,3,55);create table c(
cno int,
cname varchar(20),
cteacher varchar(50)
)insert into c values(1,'java','何昊');
insert into c values(2,'php','李美军');
insert into c values(3,'android','王超');-- 1.查询sc表中的何昊老师所授课程的女生的信息select s.sno,s.sname,s.age,sc.scgrade from s INNER JOIN sc on sc.sno = s.sno INNER JOIN c on sc.cno = c.cno where c.cteacher = '何昊' and s.sex = '女';-- 2.找出没有选修过何老师课程的所有学生姓名select s.sname from s where not exists(select * from sc,c where c.cno = sc.cno and c.cteacher='何昊' and sc.sno  = s.sno);-- 3.列出有不及格课程（成绩小于60）的学生的姓名select distinct s.sname from s INNER JOIN sc on sc.sno = s.sno where scgrade<60;

练习题3 ：

首先，第一步我们需要想创建库，和表格，并且把数据填写进去

use db_test;
create table celebrity(
sid int,
sname varchar(50),
sage int,
ssex varchar(50)
)INSERT INTO `celebrity`(`sid`, `sname`, `sage`, `ssex`) VALUES (1, '李白', 34, '男');
INSERT INTO `celebrity`(`sid`, `sname`, `sage`, `ssex`) VALUES (2, '杜甫', 24, '男');
INSERT INTO `celebrity`(`sid`, `sname`, `sage`, `ssex`) VALUES (3, '白居易', 31, '男');
INSERT INTO `celebrity`(`sid`, `sname`, `sage`, `ssex`) VALUES (4, '李商隐', 40, '女');
INSERT INTO `celebrity`(`sid`, `sname`, `sage`, `ssex`) VALUES (5, '苏轼', 26, '男');
INSERT INTO `celebrity`(`sid`, `sname`, `sage`, `ssex`) VALUES (6, '辛弃疾', 22, '男');create table works(
wid int,
wwork varchar(225),
wdynasty varchar(225)
)INSERT INTO `works`(`wid`, `wwork`, `wdynasty`) VALUES (1, '将进酒', '唐代');
INSERT INTO `works`(`wid`, `wwork`, `wdynasty`) VALUES (2, '蜀道难', '唐代');
INSERT INTO `works`(`wid`, `wwork`, `wdynasty`) VALUES (3, '夜雨寄北', '唐代');
INSERT INTO `works`(`wid`, `wwork`, `wdynasty`) VALUES (4, '静夜思', '唐代');
INSERT INTO `works`(`wid`, `wwork`, `wdynasty`) VALUES (5, '望岳', '唐代');
INSERT INTO `works`(`wid`, `wwork`, `wdynasty`) VALUES (6, '钱塘湖春行', '南宋');
INSERT INTO `works`(`wid`, `wwork`, `wdynasty`) VALUES (7, '念奴娇赤壁怀古', '北宋');
INSERT INTO `works`(`wid`, `wwork`, `wdynasty`) VALUES (8, '水调歌头', '唐代');create table summary(
sid int,
wid int,
sassess varchar(255)
)INSERT INTO `summary`(`sid`, `wid`, `sassess`) VALUES (1, 1, '天生我材必有用');
INSERT INTO `summary`(`sid`, `wid`, `sassess`) VALUES (1, 2, '危乎高哉！');
INSERT INTO `summary`(`sid`, `wid`, `sassess`) VALUES (6, 8, '明月几时有');
INSERT INTO `summary`(`sid`, `wid`, `sassess`) VALUES (3, 6, '乱花渐欲迷人眼');
INSERT INTO `summary`(`sid`, `wid`, `sassess`) VALUES (4, 3, '却话巴山夜雨时');
INSERT INTO `summary`(`sid`, `wid`, `sassess`) VALUES (5, 7, '大江东去');
INSERT INTO `summary`(`sid`, `wid`, `sassess`) VALUES (2, 5, '一览众山小');
INSERT INTO `summary`(`sid`, `wid`, `sassess`) VALUES (1, 4, '举头望明月');-- 1. 查询名人表中性别是男的作者select sname from celebrity where ssex = '男';-- 2. 查询静夜思的作者select ce.sname from works INNER JOIN summary ary on ary.wid = works.wid INNER JOIN celebrity ce on ary.sid = ce.sid where wwork = '静夜思';-- 3. 查询李白和杜甫的年纪select sage from celebrity where sname BETWEEN '李白' and '杜甫';-- 4.查询名人表中的男女人数select count(*),ssex from celebrity GROUP BY ssex;-- 5.查询白居易写的作品的名称和对应的名句select works.wwork,summary.sassess from works INNER JOIN summary on works.wid = summary.wid INNER JOIN celebrity on summary.sid = celebrity.sid where sname = '白居易';-- 6.查询年纪在25到30之间的个数select count(*)from celebrity where sage BETWEEN 25 and 30;-- 7.查询名人表中年纪最小两条的数据信息select * from celebrity ORDER BY sage limit 0,2;-- 8.查询李白的作品名称，名句和年纪select wo.wwork,ary.sassess,cel.sage from celebrity cel INNER JOIN summary ary on cel.sid = ary.sid INNER JOIN works wo on wo.wid = ary.wid where sname = '李白';-- 9.将作品为望岳的朝代修改为北宋update works set wdynasty = '北宋' where wwork = '望岳';-- 10.新增名人表中的一个作者王维，年纪25，性别男insert into celebrity values(7,'王维',25,'男');

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