总结MySQL的高级查询(二)

知识点：EXISTS子查询、NOT EXISTS子查询、分页查询、UNION联合查询

一.单词部分

①exist存在②temp临时的③district区域

④content内容⑤temporary暂时的

二.预习部分

1.表连接都可以用子查询替换吗

是的

2.检测某列是否存在某个范围可以在子查询中使用什么关键字

EXISTS

3.哪些sql语句可以嵌套子查询

较复杂的数据查询语句  需要多个表的数据的时候

子查询可以出现在任何表达式出现的位置

三.练习部分

1.查询S2学员考试成绩信息

#上机1
SELECT `studentNo`,`subjectNo`,`studentResult`,`exameDate` FROM `result`
WHERE  EXISTS(SELECT `studentNo` FROM `student` WHERE gradeId=2)
AND studentNo IN(SELECT `studentNo` FROM `student` WHERE gradeId=2)

2.制作学生成绩单

#上机2
SELECT `studentName` AS 姓名,`gradeName` AS 课程所属年级,`subjectName` AS 课程名称,`exameDate` AS 考试日期 FROM (
SELECT `studentName`,`gradeName`,`subjectName`,`exameDate` FROM `grade` AS gr,`result` AS re,`student` AS stu,`subject` AS sub
WHERE gr.`gradeID`=stu.`gradeID` AND re.`studentNo`=stu.`studentNo`
AND re.`subjectNo`=sub.`subjectNo`
) AS tempt;

3.统计Logic Java课程最近一次考试学生应到人数，实到人数和缺考人数

提取结果到临时表

#上机3
#select subjectNo from `subject` where `subjectName`='Logic Java';

#select max(`exameDate`) from result inner join `subject` on `result`.`subjectNo`=`subject`.`subjectNo`
#where `subjectName`='Logic Java';

#select `gradeID` from `subject` where `subjectName`='Logic Java';
#应到人数
SELECT COUNT(*) AS 应到人数 FROM student
WHERE `gradeID`=(SELECT `gradeID` FROM `subject` WHERE `subjectName`='Logic Java');
#实到人数
SELECT COUNT(*) AS 实到人数 FROM result
WHERE `subjectNo`=(SELECT subjectNo FROM `subject` WHERE `subjectName`='Logic Java')
AND exameDate=(SELECT MAX(`exameDate`) FROM result INNER JOIN `subject` ON `result`.`subjectNo`=`subject`.`subjectNo`
WHERE `subjectName`='Logic Java');
#缺考人数
SELECT((SELECT COUNT(*) FROM student
WHERE `gradeID`=(SELECT `gradeID` FROM `subject` WHERE `subjectName`='Logic Java'))-
(SELECT COUNT(*) FROM result
WHERE `subjectNo`=(SELECT subjectNo FROM `subject` WHERE `subjectName`='Logic Java')
AND exameDate=(SELECT MAX(`exameDate`) FROM result INNER JOIN `subject` ON `result`.`subjectNo`=`subject`.`subjectNo`
WHERE `subjectName`='Logic Java'))) AS 缺考人数;

/*select studentName,student.studentNo,studentResult
from student,result
where student.`studentNo`=result.`studentNo`*/
#添加到表
DROP TABLE IF EXISTS tempResult;
CREATE TABLE  tempResult(
SELECT studentName,student.studentNo,studentResult
FROM student,result
WHERE student.`studentNo`=result.`studentNo`
)

4.分页查询显示出租房屋信息

#上机4
DROP DATABASE IF EXISTS `house`;

CREATE DATABASE house;
USE house;
#客户信息表
DROP TABLE IF EXISTS `sys_user`;

CREATE TABLE `sys_user`(

`uid`  INT(4) NOT NULL COMMENT '客户编号' AUTO_INCREMENT PRIMARY KEY,

`uName`  VARCHAR(50) COMMENT '客户姓名',

`uPassWord`  VARCHAR(50) COMMENT '客户密码'
);

#区县信息表
DROP TABLE IF EXISTS `hos_district`;

CREATE TABLE `hos_district`(

`did`  INT(4) NOT NULL COMMENT '区县编号' AUTO_INCREMENT PRIMARY KEY,

`dName`  VARCHAR(50) NOT NULL COMMENT '区县名称'
);

#街道信息表这里有一个外键
DROP TABLE IF EXISTS `hos_street`;

CREATE TABLE `hos_street`(

`sid`  INT(4) NOT NULL COMMENT '街道编号' AUTO_INCREMENT PRIMARY KEY,

`sName`  VARCHAR(50) COMMENT '街道名称',

`sDid`  INT(4) NOT NULL COMMENT '区县编号'
);

#房屋类型表
DROP TABLE IF EXISTS `hos_type`;

CREATE TABLE `hos_type`(

`hTid`  INT(4) NOT NULL COMMENT '房屋类型编号' AUTO_INCREMENT PRIMARY KEY,

`htName`  VARCHAR(50) NOT NULL COMMENT '房屋类型名称'
);

#出租房屋信息表
DROP TABLE IF EXISTS `hos_house`;

CREATE TABLE `hos_house`(

`hMid`  INT(4) NOT NULL COMMENT '出租房屋编号' AUTO_INCREMENT PRIMARY KEY,

`uid`  INT(4) NOT NULL COMMENT '客户编号',

`sid`  INT(4) NOT NULL COMMENT '区县编号',

`hTid`  INT(4) NOT NULL COMMENT '房屋类型编号',

`price`  DECIMAL NOT NULL COMMENT '每月租金',

`topic`  VARCHAR(50) NOT NULL COMMENT '标题',

`contents`  VARCHAR(255) NOT NULL COMMENT '描述',

`hTime`  TIMESTAMP NOT NULL COMMENT '发布时间' DEFAULT NOW(),

`copy`  VARCHAR(255) NOT NULL COMMENT '备注'
);

#各个约束信息

#街道信息的区县编号外键id
ALTER TABLE `hos_street` ADD CONSTRAINT fk_stree_distr
FOREIGN KEY (`sDid`) REFERENCES `hos_district` (`did`);

#出租屋信息和各个表的联系
ALTER TABLE `hos_house` ADD CONSTRAINT fk_house_user
FOREIGN KEY (`uid`) REFERENCES `sys_user` (`uid`);

ALTER TABLE `hos_house` ADD CONSTRAINT fk_house_street
FOREIGN KEY (`sid`) REFERENCES `hos_street` (`sid`);

ALTER TABLE `hos_house` ADD CONSTRAINT fk_house_type
FOREIGN KEY (`hTid`) REFERENCES `hos_type` (`hTid`);

#默认约束
ALTER TABLE `hos_house` ALTER COLUMN `price` SET DEFAULT 0;

#ALTER TABLE `hos_house` ALTER COLUMN `hTime` SET DEFAULT now();

#添加信息

#用户表
INSERT INTO `house`.`sys_user` (`uName`, `uPassWord`) VALUES ('小漠', '123'),
('百顺', '123'),
('练基', '123'),
('冬梅', '123');

#区县信息表
INSERT INTO `house`.`hos_district` (`dName`) VALUES ('海淀区'),
('东城区'),
('南城区'),
('西城区'),
('开发区');

#街道信息表
INSERT INTO `house`.`hos_street` (`sName`) VALUES ('万泉');
INSERT INTO `house`.`hos_street` (`sName`, `sDid`) VALUES ('万泉', '1');
INSERT INTO `house`.`hos_street` (`sName`, `sDid`) VALUES ('中关', '3');
INSERT INTO `house`.`hos_street` (`sName`, `sDid`) VALUES ('万嘉', '4');
INSERT INTO `house`.`hos_street` (`sName`, `sDid`) VALUES ('海风', '5');

#房屋类型表
INSERT INTO `house`.`hos_type` (`htName`) VALUES ('一室一厅');
INSERT INTO `house`.`hos_type` (`htName`) VALUES ('两室一厅');
INSERT INTO `house`.`hos_type` (`htName`) VALUES ('三室一厅');
INSERT INTO `house`.`hos_type` (`htName`) VALUES ('两室一卫');
INSERT INTO `house`.`hos_type` (`htName`) VALUES ('一室一卫');

#出租房屋信息表
INSERT INTO `house`.`hos_house` (`uid`, `sid`, `hTid`, `price`, `topic`, `contents`, `hTime`, `copy`)
VALUES ('1', '1', '1', '530', '观景房', '阳台观赏大海', '2017-7-7', '需要的速度买');
INSERT INTO `house`.`hos_house` (`uid`, `sid`, `hTid`, `price`, `topic`, `contents`, `hTime`, `copy`)
VALUES ('2', '2', '2', '430', '大床房', '舒服睡觉', '2017-6-9', '好舒服');
INSERT INTO `house`.`hos_house` (`uid`, `sid`, `hTid`, `price`, `topic`, `contents`, `hTime`, `copy`)
VALUES ('3', '3', '3', '480', '双人房', '嘿嘿嘿', '2016-9-9', '懂不懂');
INSERT INTO `house`.`hos_house` (`uid`, `sid`, `hTid`, `price`, `topic`, `contents`, `hTime`, `copy`)
VALUES ('4', '4', '4', '360', '单人房', '旅行必选', '2015-8-8', '等你来选');

#上机4
CREATE TEMPORARY TABLE temp_house
(SELECT * FROM `hos_house` LIMIT 2,2);
SELECT * FROM temp_house;

5.查询指定客户发布的出租屋信息

#上机5
#select `uid` from `sys_user` where uName='大漠';
SELECT `dName`,`sName`,hou.`hTid`,`price`,`topic`,`contents`,`hTime`,`copy`
FROM `hos_house` AS hou,`hos_district` AS dist,`hos_street` AS str,`sys_user` AS us,`hos_type` AS ty
WHERE hou.`uid`=us.`uid` AND hou.`hTid`=ty.`hTid` AND hou.`sid`=str.`sid` AND str.`sDid`=dist.`did`
AND hou.`uid`=(SELECT `uid` FROM `sys_user` WHERE uName='大漠');

6.按区县制作房屋出租清单

#上机6
/*select sid from `hos_house` group by sid having count(sid)>1;
select `sDid` from `hos_street`
where sid=(SELECT sid FROM `hos_house` GROUP BY sid HAVING COUNT(sid)>1);
select `dName` from `hos_district` where `did`=(SELECT `sDid` FROM `hos_street`
WHERE sid=(SELECT sid FROM `hos_house` GROUP BY sid HAVING COUNT(sid)>1));*/
SELECT `htName`,`uName`,`dName`,`sName`
FROM `hos_house` AS hou,`hos_district` AS dist,`hos_street` AS str,`sys_user` AS us,`hos_type` AS ty
WHERE hou.`uid`=us.`uid` AND hou.`hTid`=ty.`hTid` AND hou.`sid`=str.`sid` AND str.`sDid`=dist.`did`
AND hou.sid=(SELECT sid FROM `hos_house` GROUP BY sid HAVING COUNT(sid)>1);

7.按区县制作房屋出租清单

#上机7 QUARTER(NOW())获取季度
/*FROM `hos_house` AS hou,`hos_district` AS dist,`hos_street` AS str,`sys_user` AS us,`hos_type` AS ty
GROUP BY hou.`hMid`
WHERE hou.`uid`=us.`uid` AND hou.`hTid`=ty.`hTid` AND hou.`sid`=str.`sid` AND str.`sDid`=dist.`did`*/

SELECT QQ AS '季度',dist.`dName` AS '区县',str.`sName` AS '街道',
ty.`htName` AS '户型',CNT AS '房屋数量'
FROM
(
 SELECT QUARTER(`hTime`) AS QQ,`sid` AS SI,`hTid` AS HT,COUNT(*) CNT
 FROM `hos_house` AS hou
 WHERE QUARTER(`hTime`)
 GROUP BY QUARTER(`hTime`),`sid`,`hTid`
 ) AS temp,`hos_district` dist,`hos_street` AS str,`hos_type` AS ty,`hos_house` AS hou
WHERE hou.`hTid`=ty.`hTid` AND hou.`sid`=str.`sid` AND str.`sDid`=dist.`did`

UNION

SELECT QUARTER(`hTime`),`hos_district`.`dName`,' 小计 ','  ',COUNT(*) AS '房屋数量'
FROM `hos_house`
INNER JOIN `hos_street` ON(hos_house.`sid`=hos_street.`sid`)
INNER JOIN hos_district ON(hos_street.`sDid`=hos_district.`did`)
WHERE QUARTER(`hTime`)
GROUP BY QUARTER(`hTime`),hos_district.`dName`
UNION

SELECT QUARTER(`hTime`),' 合计 ','  ','  ',COUNT(*) AS '房屋数量'
FROM hos_house
WHERE QUARTER(`hTime`)
GROUP BY QUARTER(`hTime`)
ORDER BY 1,2,3,4

五.总结

UNION有点陌生其它没什么。。。。。

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