[MySQL光速入門]005 查詢數據

select

數據表三連

• 查看錶結構

desc table_name;
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• 查看建表語句

show create table table_name;
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• 查看錶裏的數據

select * from table_name;
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單表查詢

簡單查詢

• 查詢全部行和列

  select * from 表名稱;

  select * from book;
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• 查詢部分列

  select 字段名稱1, 字段名稱2 from 表名稱;

  select `bookid`,`bookname` from book;
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• 查詢計算列

  select 字段名稱1, 字段名稱2,字段名稱3 * 字段名稱4 from 表名稱;

  select `bookid`,`bookname`,bookprice * borrowsum from book;
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• 使用別名

  select 字段名稱1 as 自定義名稱1, 字段名稱2 as 自定義名稱2, 字段名稱3 * 字段名稱4 as 自定義名稱3 from 表名;

  select `bookid` as 圖書ID,`bookname` as 圖書名稱,bookprice * borrowsum as 圖書總價 from book;
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• 消除重複行

  select distinct 字段名稱 from 表名稱;

  select distinct `borrowsum` from book;
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條件查詢

• 簡單條件查詢

  select * from 表名稱 where 條件;

  select * from book where borrowsum > 10;
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• 複合條件查詢

  select * from book where 條件1 and 條件2;

  select * from book where borrowsum >= 10 and typeid =3;
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• 指定範圍查詢

  select * from 表名 where 條件1 and 條件2;

  select * from book where borrowsum >= 10 and borrowsum <= 30;
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  select * from 表名 where 條件1 or 條件2;

  select * from book where borrowsum < 10 or borrowsum > 30;
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  select * from 表名 where 字段名 between 值1 and 值2;

  select * from book where borrowsum between 10 and 30;
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  select * from 表名 where 字段 not between 值1 and 值2;

  select * from book where borrowsum not between 10 and 30;
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• 指定集合查詢

  select * from 表名 where 字段 in (值1,值2);

  select * from book where bookname in ('離散數學','Java程序設計');
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  select * from 表名 where 字段 not in (值1,值2);

  select * from book where bookname not in ('離散數學','Java程序設計');
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• 查詢值爲空的行

  select * from 表名 where 字段名 is null;

  select * from bookborrow where fine is null;
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• 模糊查詢

  select * from 表名 where 字段名 like '字段值_';

  select * from book where bookname like 'java_';
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  select * from 表名 where 字段名 like '%字段值';

  select * from book where bookname like '%java';
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  select * from 表名 where 字段名 like '%字段值%';

  select * from book where bookname like '%java%';
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  select * from 表名 where 字段名 like '字段值%';

  select * from book where bookname like 'java%';
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尋找高富帥...

建表語句

drop table if exists `user`;

CREATE TABLE `user` (
  `user_id` int(11) NOT NULL AUTO_INCREMENT COMMENT '用戶主鍵id',
  `user_name` varchar(25) NOT NULL COMMENT '用戶姓名',
  `user_sex` tinyint(1) NOT NULL COMMENT '用戶性別 男生1 女生2',
  `user_height` int(11) NOT NULL COMMENT '用戶身高(cm)',
  `user_weight` int(11) NOT NULL COMMENT '用戶體重(kg)',
  `user_account` double(20,0) NOT NULL COMMENT '用戶帳戶(精確到分)',
  `user_appearance` tinyint(2) NOT NULL COMMENT '顏值, 1-10, 分數越高, 顏值越高',
  PRIMARY KEY (`user_id`)
) ENGINE=InnoDB AUTO_INCREMENT=0 DEFAULT CHARSET=utf8;
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插入數據

INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('王思聰', 1, 180, 88, 999900000.00, 6);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('陳偉霆', 1, 177, 66, 88880000.00, 9);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('鹿晗', 1, 170, 64, 77770000.00, 10);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('劉詩詩', 2, 166, 52, 66660000.00, 9);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('劉德華', 1, 165, 72,999960000.00, 9);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('張藝興', 1, 166, 70,55550000.00, 8);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('張嘉倪', 2, 155, 56,44440000.00, 6);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('黃子韜', 1, 177, 66,44443333.00, 5);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('周筆暢', 2, 160, 54,5550000.00, 4);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('陳小紜', 2, 159, 66,67890000.00, 6);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('喬振宇', 1, 188,66, 67890000.00, 5);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('趙麗穎', 2, 171,50, 77890000.00, 7);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('王鷗', 1,  199,55, 3990000.00, 8);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('蔡徐坤', 1, 187, 45, 59080000.00, 8);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('Angelababy', 2, 177, 55, 45890000.00, 8);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('張雲雷', 1, 183,69, 45670000.00, 8);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('迪麗熱巴', 2, 155, 55, 458910000.00, 8);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('朱一龍', 1, 180, 70, 78950000.00, 6);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('鄭爽', 2, 162, 56, 78540000.00, 8);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('沈騰', 1, 175, 70, 3890000.00, 7);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('雷傑', 1, 179, 70, 34560000.00, 8);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('關曉彤', 2, 165, 55, 43440000.00, 6);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('許凱', 1, 192,66, 34560000.55, 7);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('焦俊豔', 2, 155, 56, 67890000.00, 5);
INSERT INTO `user`(`user_name`, `user_sex`, `user_height`, `user_weight`, `user_account`, `user_appearance`) VALUES ('馬麗', 2, 161, 55, 34560000.00, 7);
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排序

• desc

  select * from 表名 order by 字段值 desc;

  select * from book order by bookprice desc;
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• asc

  select *from 表名 order by 字段值 asc;

  select *from book order by bookprice asc;
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• 多字段排序

  select * from 表名 order by 字段名1 asc, 字段名2 desc;

  select * from book order by borrowsum asc ,typeid desc;
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  select * from 表名 order by 字段名1, 字段名2 desc;

  select * from book order by borrowsum, typeid desc;
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限制條數

select * from 表名 limit 查詢個數;

select * from book limit 3;
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select * from 表名 limit 開始位置, 查詢個數;

select * from book limit 0, 3;
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select * from book limit 1, 3;
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聚合函數

• 最大值(max)

  select max(字段名) as '自定義名稱' from 表名;

  select max(bookprice) as '最貴的書' from book;
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• 最小值(min)

  select min(字段名) as '自定義名稱...' from 表名;

  select min(borrowsum) as '最受嫌棄的書...' from book;
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• 數量(count)

  select count(字段名) from 表名;

  select count(bookid) from book;
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• 總和(sum)

  select sum(字段名) from 表名;

  select sum(borrowsum) from book;
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• 平均值(avg)

  select avg(字段名) from 表名;

  select avg(bookprice) from book;
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分組查詢

• 簡單分組

  select 字段名1, count(字段名2) from 表名 group by 字段名1;

  select borrowsum, count(bookid) from book group by borrowsum;
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• 篩選分組結果

  select 字段1, count(字段2) from 表名 group by 字段1 having count(字段2) = 1;

  select borrowsum, count(bookid) from book group by borrowsum having count(bookid) = 1;
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• 分組排序

  select 字段1, count(字段2) from 表名 group by 字段1 order by count(字段2) desc;

  select borrowsum, count(bookid) from book group by borrowsum order by count(bookid) desc;
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• 統計功能分組查詢

  select 字段1,group_concat(字段2) from 表名 group by 字段1 order by 字段1 desc;

  select borrowsum,group_concat(bookname) from book group by borrowsum order by borrowsum desc;
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• 多個分組查詢

  select 字段1, 字段2, 聚合函數 from 表名稱 group by 字段1, 字段2;

  建表語句以及插入數據

  -- ----------------------------
  -- Table structure for choose_course
  -- ----------------------------
  DROP TABLE IF EXISTS `choose_course`;
  CREATE TABLE `choose_course` (
    `course_name` char(10) DEFAULT NULL,
    `semester_number` int(11) DEFAULT NULL,
    `student_name` char(20) DEFAULT NULL
  ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
  -- ----------------------------
  -- Records of choose_course
  -- ----------------------------
  INSERT INTO `choose_course` VALUES ('語文', '1', '李雷');
  INSERT INTO `choose_course` VALUES ('語文', '1', '韓梅梅');
  INSERT INTO `choose_course` VALUES ('語文', '1', '露西');
  INSERT INTO `choose_course` VALUES ('語文', '2', '莉莉');
  INSERT INTO `choose_course` VALUES ('語文', '2', '格林');
  INSERT INTO `choose_course` VALUES ('數學', '1', '李雷');
  INSERT INTO `choose_course` VALUES ('數學', '1', '名字真難起...');
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  查詢語句(查詢每門課, 每一個學期, 都被多少同窗選擇)

  SELECT
  	course_name,
  	semester_number,
  	count('hello')
  FROM
  	choose_course
  GROUP BY
  	course_name,
  	semester_number;
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多表查詢

內鏈接

• 使用from子句

  SELECT * FROM 表名1, 表名2;

  SELECT * FROM book, reader;
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  select 表1.字段1, 表1.字段2, 表2.字段1, 表2.字段2 from 表1,表2;

  select book.bookid,book.bookname,reader.readerid,reader.readername from book,reader;
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• 在where中指定鏈接條件

  SELECT * FROM 表1, 表2 WHERE 表2.字段 = 表1.字段;

  SELECT * FROM readertype, reader WHERE reader.retypeid = readertype.retypeid;
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• 使用join關鍵字實現鏈接

  select * from 表1 join 表2 on 表2.字段 = 表1.字段;

  select * from readertype join reader on reader.retypeid = readertype.retypeid;
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• 爲數據表使用別名

  select 表1.字段1, 表1.字段2, 表2.字段1 from 表1 join 表2 on 表2.字段 = 表1.字段;

  select readertype.retypeid,readertype.borrowquantity,reader.readerstatus from readertype join reader on reader.retypeid = readertype.retypeid;
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  select 別名1.字段1, 別名1.字段2, 別名2.字段 from 表1 as 別名1 join 表2 as 別名2 on 別名2.字段 = 別名1.字段;

  select a.retypeid,a.borrowquantity,b.readerstatus from readertype as a join reader as b on b.retypeid = a.retypeid;
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• 三個錶鏈接查詢

  select 表1.字段,表2.字段,表3.字段 from 表1 join 表2 on 表1.字段 = 表2.字段 join 表3 on 表3.字段 = 表1.字段;

  select bookborrow.borrowid,bookstorage.bookstatus,reader.readername from bookborrow join bookstorage on bookborrow.bookbarcode = bookstorage.bookbarcode join reader on reader.readerid = bookborrow.readerid;
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  select 表1.字段, 表2.字段, 表3.字段 from 表1 join 表2 on 表2.字段 = 表1.字段 join 表3 on 表3.字段 = 表2.字段;

  select bookstorage.bookintime,book.bookname,booktype.typename from bookstorage join book on book.bookid = bookstorage.bookid join booktype on booktype.typeid = book.typeid;
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  select 表1.字段, 表2.字段, 表3.字段 from 表1 inner join 表2 on 表2.字段 = 表1.字段 inner join 表3 on 表3.字段 = 表2.字段;

  select bookstorage.bookintime,book.bookname,booktype.typename from bookstorage inner join book on book.bookid = bookstorage.bookid inner join booktype on booktype.typeid = book.typeid;
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外鏈接

set foreign_key_checks=0;
drop table if exists `user`;
drop table if exists `user_detail`;
create table user(
	user_id int(11) primary key auto_increment not null,
	user_name varchar(20) not null ,
	user_sex tinyint(1) not null default 1 comment '1 for male 2 for female'
);
create table user_detail(
	user_detail_id int(11) not null primary key auto_increment,
	user_detail_address varchar(255) default '河南平頂山' not null,
	user_detail_phone char(11) not null unique,
	user_detail_uid int(11) not null,
	foreign key(user_detail_uid) REFERENCES user(user_id)
);
insert into user(`user_name`) values('張三');
insert into user(`user_name`) values('李四');
insert into user(`user_name`) values('王五');
insert into user(`user_name`) values('趙六');
insert into user(`user_name`) values('錢七');
insert into user(`user_name`) values('孫八');
insert into user(`user_name`) values('周老九');
insert into user(`user_name`) values('吳老十');
INSERT INTO `user_detail` VALUES (1, '河南平頂山', '15639279531', 1);
INSERT INTO `user_detail` VALUES (2, '河南平頂山', '15639279532', 2);
INSERT INTO `user_detail` VALUES (3, '河南平頂山', '15639279533', 3);
INSERT INTO `user_detail` VALUES (4, '河南平頂山', '15639279534', 4);
INSERT INTO `user_detail` VALUES (11, '河南平頂山', '15639279521', 11);
INSERT INTO `user_detail` VALUES (12, '河南平頂山', '15639279522', 12);
INSERT INTO `user_detail` VALUES (13, '河南平頂山', '15639279523', 13);
INSERT INTO `user_detail` VALUES (14, '河南平頂山', '15639279524', 14);
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• 左外鏈接

  select * from 表1 left join 表2 on 表1.字段 = 表2.字段;

  select * from user left join user_detail on user.user_id = user_detail.user_detail_uid;
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  select * from 表2 right join 表1 on 表1.字段 = 表2.字段;

  select * from user_detail right join user on user.user_id = user_detail.user_detail_uid;
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• 右外鏈接

  select * from 表1 right join 表2 on 表1.字段 = 表2.字段;

  select * from user right join user_detail on user.user_id = user_detail.user_detail_uid;
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• 內鏈接

  select * from 表1 inner join 表2 on 表2.字段 = 表1.字段;

  select * from user inner join user_detail on user_detail.user_detail_uid = user.user_id;
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  select * from 表1 join 表2 on 表2.字段 = 表1.字段;

  select * from user join user_detail on user_detail.user_detail_uid = user.user_id;
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交叉鏈接

如下兩句, 效果同樣

select * from 表1 cross join 表2 ;

select * from user cross join user_detail ;
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select * from 表1,表2;

select * from user,user_detail;
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如下兩句, 效果同樣

select * from 表1 cross join 表2 on 表2.字段 = 表1.字段;

select * from user cross join user_detail on user_detail.user_detail_uid = user.user_id;
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select * from 表1,表2 where 表1.字段 = 表2.字段;

select * from user,user_detail where user.user_id = user_detail.user_detail_uid;
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自鏈接

如下兩句, 效果同樣

select 表別名1.字段1, 表別名1.字段2 from 表名 as 表別名1,表名 as 表別名2 where 表別名1.字段2 > 表別名2.字段2 and 表別名2.字段1 = '字段值' order by 表別名1.`字段2 desc,表別名1.字段1

SELECT
	b2.bookname,
	b2.borrowsum 
FROM
	book AS b2,
	book AS b1 
WHERE
	b2.borrowsum > b1.borrowsum 
	AND b1.bookname = '中醫的故事' 
ORDER BY
	b2.borrowsum DESC,
	b2.bookname;
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SELECT
	b2.bookname,
	b2.borrowsum 
FROM
	book AS b2 join
	book AS b1 
on
	b2.borrowsum > b1.borrowsum 
	where b1.bookname = '中醫的故事' 
ORDER BY
	b2.borrowsum DESC,
	b2.bookname;
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select 字段1,字段2 from 表名 where 字段3 > (select 字段3 from 表名 where 字段1='字段值') order by 字段2 desc, 字段1;

select bookname,borrowsum from book where bookprice > (select bookprice from book where bookname='中醫的故事') order by borrowsum desc, bookname;
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聯合查詢

select * from 表1 left join 表2 on 表1.字段 = 表2.字段 union select * from 表1 right join 表2 on 表1.字段 = 表2.字段;

select * from user left join user_detail on user.user_id = user_detail.user_detail_uid union select * from user right join user_detail on user.user_id = user_detail.user_detail_uid;
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子查詢

使用比較運算符的子查詢

• 查詢價格高於機械設計手冊的書籍的書籍號, 書籍名稱, 書籍單價, 價格從高到低排序

SELECT
	bookid,
	bookname,
	bookprice
FROM
	book 
WHERE
	bookprice > ( SELECT bookprice FROM book WHERE bookname = '機械設計手冊' ) 
ORDER BY
	bookprice DESC;
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• 查詢類別是學生的讀者信息, 包括讀者編號, 讀者姓名, 發證日期

SELECT
	readerid,
	readername,
	readerdate 
FROM
	reader 
WHERE
	retypeid = ( SELECT retypeid FROM readertype WHERE typename = '學生' );
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也能夠使用連表查詢......

SELECT
	readerid,
	readername,
	readerdate 
FROM
	reader
	JOIN readertype ON readertype.retypeid = reader.retypeid 
	AND typename = '學生';
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[not] in 子查詢

• 查詢已經借出的書籍id, 書籍名稱

SELECT
	bookid,
	bookname 
FROM
	book 
WHERE
	bookid IN ( SELECT bookid FROM bookstorage WHERE bookstatus = '借出' );
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• 查詢沒有借出(在館)的書籍id, 書籍名稱

SELECT
	`bookid`,
	`bookname` 
FROM
	`book` 
WHERE
	`bookid` NOT IN ( SELECT `bookid` FROM `bookstorage` WHERE `bookstatus` = '借出' );
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SELECT
	`bookid`,
	`bookname` 
FROM
	`book` 
WHERE
	`bookid` IN ( SELECT `bookid` FROM `bookstorage` WHERE `bookstatus` != '借出' );
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any 子查詢

> any 大於最小的 < any 小於最大的 = any 至關於in();

• 選擇book表中, 價格大於機械工業出版社最便宜價格的圖書(圖書ID, 圖書名稱, 出版社, 價格)

SELECT
	`bookid`,
	`bookname`,
	`bookpublisher`,
	`bookprice` 
FROM
	`book` 
WHERE
	`bookprice` > ANY ( SELECT bookprice FROM book WHERE bookpublisher = '機械工業出版社' );
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all 子查詢

> all 大於最大的 < all 小於最小的

• 選擇book表中, 價格大於機械工業出版社最貴价格的圖書(圖書ID, 圖書名稱, 出版社, 價格)

SELECT
	`bookid`,
	`bookname`,
	`bookpublisher`,
	`bookprice` 
FROM
	`book` 
WHERE
	`bookprice` > all ( SELECT bookprice FROM book WHERE bookpublisher = '機械工業出版社' );
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[not] exists子查詢

• 查看圖書類別表中沒有圖書的類別id和類別名稱

SELECT
	typeid,
	typename 
FROM
	booktype 
WHERE
	NOT EXISTS ( SELECT * FROM book WHERE booktype.typeid = book.typeid );
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• 查看圖書類別表中有圖書的類別id和類別名稱

SELECT
	typeid,
	typename 
FROM
	booktype 
WHERE
	EXISTS ( SELECT * FROM book WHERE booktype.typeid = book.typeid );
複製代碼

快速跳轉

• [MySQL光速入門]004 做業解答
• [MySQL光速入門]006 留點做業...