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97-98复习连接查询、子查询,子查询经典案例

SQL99语法：

1.内连接

　　语法：

　　select 查询列表

　　from 表1

　　【inner】(inner可以省略，写不写都表示内连) join 表2 别名

　　on 连接条件

　　where 筛选条件

　　group by 分组列表

　　having　　分组后的筛选

　　order by　排序列表　

　　limit offset，size;

　　特点：

- 表的顺序可以调换
- 内连接的结果=多表的交集
- n表连接至少需要n-1个连接条件

　　分类：

　　　　等值连接

　　　　非等职连接

　　　　自连接

2、外连接:

　　语法：

　　select 查询列表

　　from 表1

　　left|right|full【outer】(outer可以省略) join 表2 别名

　　on 连接条件

　　where 筛选条件

　　group by 分组列表

　　having　　分组后的筛选

　　order by　排序列表　

　　limit offset，size;

　　特点：

- 查询的结果=主表中所有的行，从表和它匹配的将显示匹配行，如果从表没有匹配的则显示null
- left join左边是主表，right join右边就是主表
- full join 两边都是主表
- 一般用于查询除了交集部分的剩余的不匹配的行

3、交叉连接

　　语法：

　　　　select 查询列表

　　　　from 表名1 别名

　　　　cross join 表2 别名;

　　特点：

　　　　类似于笛卡尔乘积

子查询　

　　一、含义

　　　　嵌套在其他语句内部的select语句称为子查询或内查询，

　　　　外面的语句可以是insert、update、delete、select等，一般select作为外面语句较多

　　　　外面如果为select语句，则此语句称为外查询或主查询

　　二、分类

　　　　1.按出现的位置

　　　　select后面

　　　　　　仅仅支持标量子查询，放别的还不行，会报错

　　　　from后面

　　　　　　表子查询

　　　　作为条件，出现在where或having后面

　　　　　　标量子查询

　　　　　　列子查询

　　　　　　行子查询

　　　　exists后面

　　　　　　标量子查询

　　　　　　列子查询

　　　　　　行子查询

　　　　　　表子查询

　　　　2、按结果集的行列

　　　　标量子查询(单行子查询):结果集为一行一列

　　　　列子查询(多行子查询):结果集为多行一列

　　　　行子查询：结果集为多行多列

　　　　表子查询(嵌套子查询）：结果集为多行多列

三、示例

　　where或having后面

　　1.标量子查询

　　案例：查询最低工资的员工姓名和工资

　　(1)最低工资

　　　　select min(salary) from employees

　　(2)查询员工的姓名和工资，要求工资=(1)

　　　　select last_name,salary

　　　　from employees

　　　　where salary=(

　　　　　　select min(salary) from employees

　　　　);

2、列子查询

案例：查询所有是领导的员工姓名

(1)查询所有员工的manager_id

select manager_id

from employees;

(2)查询姓名，employee_id属于(1)列表的一个

select last_name

from employees

where employee_id in (

　　select manager_id

　　from employees

);

分页查询：

　　一、应用场景　

当要查询的条目数太多，一页显示不全

二、语法

　　　　select 查询列表

　　　　from 表

　　　　limit 【offset】，size;

　　　　注意：

　　　　　　offset代表的是起始的条目索引，默认从0开始

　　　　　　size代表的是显示的条目数

　　　　公式：

　　　　　　假如要显示的页数为page，每一页条目数为size

　　　　　　select 查询列表

　　　　　　from 表

　　　　　　limit (page-1)*size,size;

子查询经典案例：

  1 /*
  2 SQLyog Ultimate v10.00 Beta1
  3 MySQL - 5.5.15 : Database - myemployees
  4 *********************************************************************
  5 */
  6 
  7 
  8 /*!40101 SET NAMES utf8 */;
  9 
 10 /*!40101 SET SQL_MODE=''*/;
 11 
 12 /*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
 13 /*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
 14 /*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
 15 /*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;
 16 CREATE DATABASE /*!32312 IF NOT EXISTS*/`myemployees` /*!40100 DEFAULT CHARACTER SET gb2312 */;
 17 
 18 USE `myemployees`;
 19 
 20 /*Table structure for table `departments` */
 21 
 22 DROP TABLE IF EXISTS `departments`;
 23 
 24 CREATE TABLE `departments` (
 25   `department_id` int(4) NOT NULL AUTO_INCREMENT,
 26   `department_name` varchar(3) DEFAULT NULL,
 27   `manager_id` int(6) DEFAULT NULL,
 28   `location_id` int(4) DEFAULT NULL,
 29   PRIMARY KEY (`department_id`),
 30   KEY `loc_id_fk` (`location_id`),
 31   CONSTRAINT `loc_id_fk` FOREIGN KEY (`location_id`) REFERENCES `locations` (`location_id`)
 32 ) ENGINE=InnoDB AUTO_INCREMENT=271 DEFAULT CHARSET=gb2312;
 33 
 34 /*Data for the table `departments` */
 35 
 36 insert  into `departments`(`department_id`,`department_name`,`manager_id`,`location_id`) values (10,'Adm',200,1700),(20,'Mar',201,1800),(30,'Pur',114,1700),(40,'Hum',203,2400),(50,'Shi',121,1500),(60,'IT',103,1400),(70,'Pub',204,2700),(80,'Sal',145,2500),(90,'Exe',100,1700),(100,'Fin',108,1700),(110,'Acc',205,1700),(120,'Tre',NULL,1700),(130,'Cor',NULL,1700),(140,'Con',NULL,1700),(150,'Sha',NULL,1700),(160,'Ben',NULL,1700),(170,'Man',NULL,1700),(180,'Con',NULL,1700),(190,'Con',NULL,1700),(200,'Ope',NULL,1700),(210,'IT ',NULL,1700),(220,'NOC',NULL,1700),(230,'IT ',NULL,1700),(240,'Gov',NULL,1700),(250,'Ret',NULL,1700),(260,'Rec',NULL,1700),(270,'Pay',NULL,1700);
 37 
 38 /*Table structure for table `employees` */
 39 
 40 DROP TABLE IF EXISTS `employees`;
 41 
 42 CREATE TABLE `employees` (
 43   `employee_id` int(6) NOT NULL AUTO_INCREMENT,
 44   `first_name` varchar(20) DEFAULT NULL,
 45   `last_name` varchar(25) DEFAULT NULL,
 46   `email` varchar(25) DEFAULT NULL,
 47   `phone_number` varchar(20) DEFAULT NULL,
 48   `job_id` varchar(10) DEFAULT NULL,
 49   `salary` double(10,2) DEFAULT NULL,
 50   `commission_pct` double(4,2) DEFAULT NULL,
 51   `manager_id` int(6) DEFAULT NULL,
 52   `department_id` int(4) DEFAULT NULL,
 53   `hiredate` datetime DEFAULT NULL,
 54   PRIMARY KEY (`employee_id`),
 55   KEY `dept_id_fk` (`department_id`),
 56   KEY `job_id_fk` (`job_id`),
 57   CONSTRAINT `dept_id_fk` FOREIGN KEY (`department_id`) REFERENCES `departments` (`department_id`),
 58   CONSTRAINT `job_id_fk` FOREIGN KEY (`job_id`) REFERENCES `jobs` (`job_id`)
 59 ) ENGINE=InnoDB AUTO_INCREMENT=207 DEFAULT CHARSET=gb2312;
 60 
 61 /*Data for the table `employees` */
 62 
 63 insert  into `employees`(`employee_id`,`first_name`,`last_name`,`email`,`phone_number`,`job_id`,`salary`,`commission_pct`,`manager_id`,`department_id`,`hiredate`) values (100,'Steven','K_ing','SKING','515.123.4567','AD_PRES',24000.00,NULL,NULL,90,'1992-04-03 00:00:00'),(101,'Neena','Kochhar','NKOCHHAR','515.123.4568','AD_VP',17000.00,NULL,100,90,'1992-04-03 00:00:00'),(102,'Lex','De Haan','LDEHAAN','515.123.4569','AD_VP',17000.00,NULL,100,90,'1992-04-03 00:00:00'),(103,'Alexander','Hunold','AHUNOLD','590.423.4567','IT_PROG',9000.00,NULL,102,60,'1992-04-03 00:00:00'),(104,'Bruce','Ernst','BERNST','590.423.4568','IT_PROG',6000.00,NULL,103,60,'1992-04-03 00:00:00'),(105,'David','Austin','DAUSTIN','590.423.4569','IT_PROG',4800.00,NULL,103,60,'1998-03-03 00:00:00'),(106,'Valli','Pataballa','VPATABAL','590.423.4560','IT_PROG',4800.00,NULL,103,60,'1998-03-03 00:00:00'),(107,'Diana','Lorentz','DLORENTZ','590.423.5567','IT_PROG',4200.00,NULL,103,60,'1998-03-03 00:00:00'),(108,'Nancy','Greenberg','NGREENBE','515.124.4569','FI_MGR',12000.00,NULL,101,100,'1998-03-03 00:00:00'),(109,'Daniel','Faviet','DFAVIET','515.124.4169','FI_ACCOUNT',9000.00,NULL,108,100,'1998-03-03 00:00:00'),(110,'John','Chen','JCHEN','515.124.4269','FI_ACCOUNT',8200.00,NULL,108,100,'2000-09-09 00:00:00'),(111,'Ismael','Sciarra','ISCIARRA','515.124.4369','FI_ACCOUNT',7700.00,NULL,108,100,'2000-09-09 00:00:00'),(112,'Jose Manuel','Urman','JMURMAN','515.124.4469','FI_ACCOUNT',7800.00,NULL,108,100,'2000-09-09 00:00:00'),(113,'Luis','Popp','LPOPP','515.124.4567','FI_ACCOUNT',6900.00,NULL,108,100,'2000-09-09 00:00:00'),(114,'Den','Raphaely','DRAPHEAL','515.127.4561','PU_MAN',11000.00,NULL,100,30,'2000-09-09 00:00:00'),(115,'Alexander','Khoo','AKHOO','515.127.4562','PU_CLERK',3100.00,NULL,114,30,'2000-09-09 00:00:00'),(116,'Shelli','Baida','SBAIDA','515.127.4563','PU_CLERK',2900.00,NULL,114,30,'2000-09-09 00:00:00'),(117,'Sigal','Tobias','STOBIAS','515.127.4564','PU_CLERK',2800.00,NULL,114,30,'2000-09-09 00:00:00'),(118,'Guy','Himuro','GHIMURO','515.127.4565','PU_CLERK',2600.00,NULL,114,30,'2000-09-09 00:00:00'),(119,'Karen','Colmenares','KCOLMENA','515.127.4566','PU_CLERK',2500.00,NULL,114,30,'2000-09-09 00:00:00'),(120,'Matthew','Weiss','MWEISS','650.123.1234','ST_MAN',8000.00,NULL,100,50,'2004-02-06 00:00:00'),(121,'Adam','Fripp','AFRIPP','650.123.2234','ST_MAN',8200.00,NULL,100,50,'2004-02-06 00:00:00'),(122,'Payam','Kaufling','PKAUFLIN','650.123.3234','ST_MAN',7900.00,NULL,100,50,'2004-02-06 00:00:00'),(123,'Shanta','Vollman','SVOLLMAN','650.123.4234','ST_MAN',6500.00,NULL,100,50,'2004-02-06 00:00:00'),(124,'Kevin','Mourgos','KMOURGOS','650.123.5234','ST_MAN',5800.00,NULL,100,50,'2004-02-06 00:00:00'),(125,'Julia','Nayer','JNAYER','650.124.1214','ST_CLERK',3200.00,NULL,120,50,'2004-02-06 00:00:00'),(126,'Irene','Mikkilineni','IMIKKILI','650.124.1224','ST_CLERK',2700.00,NULL,120,50,'2004-02-06 00:00:00'),(127,'James','Landry','JLANDRY','650.124.1334','ST_CLERK',2400.00,NULL,120,50,'2004-02-06 00:00:00'),(128,'Steven','Markle','SMARKLE','650.124.1434','ST_CLERK',2200.00,NULL,120,50,'2004-02-06 00:00:00'),(129,'Laura','Bissot','LBISSOT','650.124.5234','ST_CLERK',3300.00,NULL,121,50,'2004-02-06 00:00:00'),(130,'Mozhe','Atkinson','MATKINSO','650.124.6234','ST_CLERK',2800.00,NULL,121,50,'2004-02-06 00:00:00'),(131,'James','Marlow','JAMRLOW','650.124.7234','ST_CLERK',2500.00,NULL,121,50,'2004-02-06 00:00:00'),(132,'TJ','Olson','TJOLSON','650.124.8234','ST_CLERK',2100.00,NULL,121,50,'2004-02-06 00:00:00'),(133,'Jason','Mallin','JMALLIN','650.127.1934','ST_CLERK',3300.00,NULL,122,50,'2004-02-06 00:00:00'),(134,'Michael','Rogers','MROGERS','650.127.1834','ST_CLERK',2900.00,NULL,122,50,'2002-12-23 00:00:00'),(135,'Ki','Gee','KGEE','650.127.1734','ST_CLERK',2400.00,NULL,122,50,'2002-12-23 00:00:00'),(136,'Hazel','Philtanker','HPHILTAN','650.127.1634','ST_CLERK',2200.00,NULL,122,50,'2002-12-23 00:00:00'),(137,'Renske','Ladwig','RLADWIG','650.121.1234','ST_CLERK',3600.00,NULL,123,50,'2002-12-23 00:00:00'),(138,'Stephen','Stiles','SSTILES','650.121.2034','ST_CLERK',3200.00,NULL,123,50,'2002-12-23 00:00:00'),(139,'John','Seo','JSEO','650.121.2019','ST_CLERK',2700.00,NULL,123,50,'2002-12-23 00:00:00'),(140,'Joshua','Patel','JPATEL','650.121.1834','ST_CLERK',2500.00,NULL,123,50,'2002-12-23 00:00:00'),(141,'Trenna','Rajs','TRAJS','650.121.8009','ST_CLERK',3500.00,NULL,124,50,'2002-12-23 00:00:00'),(142,'Curtis','Davies','CDAVIES','650.121.2994','ST_CLERK',3100.00,NULL,124,50,'2002-12-23 00:00:00'),(143,'Randall','Matos','RMATOS','650.121.2874','ST_CLERK',2600.00,NULL,124,50,'2002-12-23 00:00:00'),(144,'Peter','Vargas','PVARGAS','650.121.2004','ST_CLERK',2500.00,NULL,124,50,'2002-12-23 00:00:00'),(145,'John','Russell','JRUSSEL','011.44.1344.429268','SA_MAN',14000.00,0.40,100,80,'2002-12-23 00:00:00'),(146,'Karen','Partners','KPARTNER','011.44.1344.467268','SA_MAN',13500.00,0.30,100,80,'2002-12-23 00:00:00'),(147,'Alberto','Errazuriz','AERRAZUR','011.44.1344.429278','SA_MAN',12000.00,0.30,100,80,'2002-12-23 00:00:00'),(148,'Gerald','Cambrault','GCAMBRAU','011.44.1344.619268','SA_MAN',11000.00,0.30,100,80,'2002-12-23 00:00:00'),(149,'Eleni','Zlotkey','EZLOTKEY','011.44.1344.429018','SA_MAN',10500.00,0.20,100,80,'2002-12-23 00:00:00'),(150,'Peter','Tucker','PTUCKER','011.44.1344.129268','SA_REP',10000.00,0.30,145,80,'2014-03-05 00:00:00'),(151,'David','Bernstein','DBERNSTE','011.44.1344.345268','SA_REP',9500.00,0.25,145,80,'2014-03-05 00:00:00'),(152,'Peter','Hall','PHALL','011.44.1344.478968','SA_REP',9000.00,0.25,145,80,'2014-03-05 00:00:00'),(153,'Christopher','Olsen','COLSEN','011.44.1344.498718','SA_REP',8000.00,0.20,145,80,'2014-03-05 00:00:00'),(154,'Nanette','Cambrault','NCAMBRAU','011.44.1344.987668','SA_REP',7500.00,0.20,145,80,'2014-03-05 00:00:00'),(155,'Oliver','Tuvault','OTUVAULT','011.44.1344.486508','SA_REP',7000.00,0.15,145,80,'2014-03-05 00:00:00'),(156,'Janette','K_ing','JKING','011.44.1345.429268','SA_REP',10000.00,0.35,146,80,'2014-03-05 00:00:00'),(157,'Patrick','Sully','PSULLY','011.44.1345.929268','SA_REP',9500.00,0.35,146,80,'2014-03-05 00:00:00'),(158,'Allan','McEwen','AMCEWEN','011.44.1345.829268','SA_REP',9000.00,0.35,146,80,'2014-03-05 00:00:00'),(159,'Lindsey','Smith','LSMITH','011.44.1345.729268','SA_REP',8000.00,0.30,146,80,'2014-03-05 00:00:00'),(160,'Louise','Doran','LDORAN','011.44.1345.629268','SA_REP',7500.00,0.30,146,80,'2014-03-05 00:00:00'),(161,'Sarath','Sewall','SSEWALL','011.44.1345.529268','SA_REP',7000.00,0.25,146,80,'2014-03-05 00:00:00'),(162,'Clara','Vishney','CVISHNEY','011.44.1346.129268','SA_REP',10500.00,0.25,147,80,'2014-03-05 00:00:00'),(163,'Danielle','Greene','DGREENE','011.44.1346.229268','SA_REP',9500.00,0.15,147,80,'2014-03-05 00:00:00'),(164,'Mattea','Marvins','MMARVINS','011.44.1346.329268','SA_REP',7200.00,0.10,147,80,'2014-03-05 00:00:00'),(165,'David','Lee','DLEE','011.44.1346.529268','SA_REP',6800.00,0.10,147,80,'2014-03-05 00:00:00'),(166,'Sundar','Ande','SANDE','011.44.1346.629268','SA_REP',6400.00,0.10,147,80,'2014-03-05 00:00:00'),(167,'Amit','Banda','ABANDA','011.44.1346.729268','SA_REP',6200.00,0.10,147,80,'2014-03-05 00:00:00'),(168,'Lisa','Ozer','LOZER','011.44.1343.929268','SA_REP',11500.00,0.25,148,80,'2014-03-05 00:00:00'),(169,'Harrison','Bloom','HBLOOM','011.44.1343.829268','SA_REP',10000.00,0.20,148,80,'2014-03-05 00:00:00'),(170,'Tayler','Fox','TFOX','011.44.1343.729268','SA_REP',9600.00,0.20,148,80,'2014-03-05 00:00:00'),(171,'William','Smith','WSMITH','011.44.1343.629268','SA_REP',7400.00,0.15,148,80,'2014-03-05 00:00:00'),(172,'Elizabeth','Bates','EBATES','011.44.1343.529268','SA_REP',7300.00,0.15,148,80,'2014-03-05 00:00:00'),(173,'Sundita','Kumar','SKUMAR','011.44.1343.329268','SA_REP',6100.00,0.10,148,80,'2014-03-05 00:00:00'),(174,'Ellen','Abel','EABEL','011.44.1644.429267','SA_REP',11000.00,0.30,149,80,'2014-03-05 00:00:00'),(175,'Alyssa','Hutton','AHUTTON','011.44.1644.429266','SA_REP',8800.00,0.25,149,80,'2014-03-05 00:00:00'),(176,'Jonathon','Taylor','JTAYLOR','011.44.1644.429265','SA_REP',8600.00,0.20,149,80,'2014-03-05 00:00:00'),(177,'Jack','Livingston','JLIVINGS','011.44.1644.429264','SA_REP',8400.00,0.20,149,80,'2014-03-05 00:00:00'),(178,'Kimberely','Grant','KGRANT','011.44.1644.429263','SA_REP',7000.00,0.15,149,NULL,'2014-03-05 00:00:00'),(179,'Charles','Johnson','CJOHNSON','011.44.1644.429262','SA_REP',6200.00,0.10,149,80,'2014-03-05 00:00:00'),(180,'Winston','Taylor','WTAYLOR','650.507.9876','SH_CLERK',3200.00,NULL,120,50,'2014-03-05 00:00:00'),(181,'Jean','Fleaur','JFLEAUR','650.507.9877','SH_CLERK',3100.00,NULL,120,50,'2014-03-05 00:00:00'),(182,'Martha','Sullivan','MSULLIVA','650.507.9878','SH_CLERK',2500.00,NULL,120,50,'2014-03-05 00:00:00'),(183,'Girard','Geoni','GGEONI','650.507.9879','SH_CLERK',2800.00,NULL,120,50,'2014-03-05 00:00:00'),(184,'Nandita','Sarchand','NSARCHAN','650.509.1876','SH_CLERK',4200.00,NULL,121,50,'2014-03-05 00:00:00'),(185,'Alexis','Bull','ABULL','650.509.2876','SH_CLERK',4100.00,NULL,121,50,'2014-03-05 00:00:00'),(186,'Julia','Dellinger','JDELLING','650.509.3876','SH_CLERK',3400.00,NULL,121,50,'2014-03-05 00:00:00'),(187,'Anthony','Cabrio','ACABRIO','650.509.4876','SH_CLERK',3000.00,NULL,121,50,'2014-03-05 00:00:00'),(188,'Kelly','Chung','KCHUNG','650.505.1876','SH_CLERK',3800.00,NULL,122,50,'2014-03-05 00:00:00'),(189,'Jennifer','Dilly','JDILLY','650.505.2876','SH_CLERK',3600.00,NULL,122,50,'2014-03-05 00:00:00'),(190,'Timothy','Gates','TGATES','650.505.3876','SH_CLERK',2900.00,NULL,122,50,'2014-03-05 00:00:00'),(191,'Randall','Perkins','RPERKINS','650.505.4876','SH_CLERK',2500.00,NULL,122,50,'2014-03-05 00:00:00'),(192,'Sarah','Bell','SBELL','650.501.1876','SH_CLERK',4000.00,NULL,123,50,'2014-03-05 00:00:00'),(193,'Britney','Everett','BEVERETT','650.501.2876','SH_CLERK',3900.00,NULL,123,50,'2014-03-05 00:00:00'),(194,'Samuel','McCain','SMCCAIN','650.501.3876','SH_CLERK',3200.00,NULL,123,50,'2014-03-05 00:00:00'),(195,'Vance','Jones','VJONES','650.501.4876','SH_CLERK',2800.00,NULL,123,50,'2014-03-05 00:00:00'),(196,'Alana','Walsh','AWALSH','650.507.9811','SH_CLERK',3100.00,NULL,124,50,'2014-03-05 00:00:00'),(197,'Kevin','Feeney','KFEENEY','650.507.9822','SH_CLERK',3000.00,NULL,124,50,'2014-03-05 00:00:00'),(198,'Donald','OConnell','DOCONNEL','650.507.9833','SH_CLERK',2600.00,NULL,124,50,'2014-03-05 00:00:00'),(199,'Douglas','Grant','DGRANT','650.507.9844','SH_CLERK',2600.00,NULL,124,50,'2014-03-05 00:00:00'),(200,'Jennifer','Whalen','JWHALEN','515.123.4444','AD_ASST',4400.00,NULL,101,10,'2016-03-03 00:00:00'),(201,'Michael','Hartstein','MHARTSTE','515.123.5555','MK_MAN',13000.00,NULL,100,20,'2016-03-03 00:00:00'),(202,'Pat','Fay','PFAY','603.123.6666','MK_REP',6000.00,NULL,201,20,'2016-03-03 00:00:00'),(203,'Susan','Mavris','SMAVRIS','515.123.7777','HR_REP',6500.00,NULL,101,40,'2016-03-03 00:00:00'),(204,'Hermann','Baer','HBAER','515.123.8888','PR_REP',10000.00,NULL,101,70,'2016-03-03 00:00:00'),(205,'Shelley','Higgins','SHIGGINS','515.123.8080','AC_MGR',12000.00,NULL,101,110,'2016-03-03 00:00:00'),(206,'William','Gietz','WGIETZ','515.123.8181','AC_ACCOUNT',8300.00,NULL,205,110,'2016-03-03 00:00:00');
 64 
 65 /*Table structure for table `jobs` */
 66 
 67 DROP TABLE IF EXISTS `jobs`;
 68 
 69 CREATE TABLE `jobs` (
 70   `job_id` varchar(10) NOT NULL,
 71   `job_title` varchar(35) DEFAULT NULL,
 72   `min_salary` int(6) DEFAULT NULL,
 73   `max_salary` int(6) DEFAULT NULL,
 74   PRIMARY KEY (`job_id`)
 75 ) ENGINE=InnoDB DEFAULT CHARSET=gb2312;
 76 
 77 /*Data for the table `jobs` */
 78 
 79 insert  into `jobs`(`job_id`,`job_title`,`min_salary`,`max_salary`) values ('AC_ACCOUNT','Public Accountant',4200,9000),('AC_MGR','Accounting Manager',8200,16000),('AD_ASST','Administration Assistant',3000,6000),('AD_PRES','President',20000,40000),('AD_VP','Administration Vice President',15000,30000),('FI_ACCOUNT','Accountant',4200,9000),('FI_MGR','Finance Manager',8200,16000),('HR_REP','Human Resources Representative',4000,9000),('IT_PROG','Programmer',4000,10000),('MK_MAN','Marketing Manager',9000,15000),('MK_REP','Marketing Representative',4000,9000),('PR_REP','Public Relations Representative',4500,10500),('PU_CLERK','Purchasing Clerk',2500,5500),('PU_MAN','Purchasing Manager',8000,15000),('SA_MAN','Sales Manager',10000,20000),('SA_REP','Sales Representative',6000,12000),('SH_CLERK','Shipping Clerk',2500,5500),('ST_CLERK','Stock Clerk',2000,5000),('ST_MAN','Stock Manager',5500,8500);
 80 
 81 /*Table structure for table `locations` */
 82 
 83 DROP TABLE IF EXISTS `locations`;
 84 
 85 CREATE TABLE `locations` (
 86   `location_id` int(11) NOT NULL AUTO_INCREMENT,
 87   `street_address` varchar(40) DEFAULT NULL,
 88   `postal_code` varchar(12) DEFAULT NULL,
 89   `city` varchar(30) DEFAULT NULL,
 90   `state_province` varchar(25) DEFAULT NULL,
 91   `country_id` varchar(2) DEFAULT NULL,
 92   PRIMARY KEY (`location_id`)
 93 ) ENGINE=InnoDB AUTO_INCREMENT=3201 DEFAULT CHARSET=gb2312;
 94 
 95 /*Data for the table `locations` */
 96 
 97 insert  into `locations`(`location_id`,`street_address`,`postal_code`,`city`,`state_province`,`country_id`) values (1000,'1297 Via Cola di Rie','00989','Roma',NULL,'IT'),(1100,'93091 Calle della Testa','10934','Venice',NULL,'IT'),(1200,'2017 Shinjuku-ku','1689','Tokyo','Tokyo Prefecture','JP'),(1300,'9450 Kamiya-cho','6823','Hiroshima',NULL,'JP'),(1400,'2014 Jabberwocky Rd','26192','Southlake','Texas','US'),(1500,'2011 Interiors Blvd','99236','South San Francisco','California','US'),(1600,'2007 Zagora St','50090','South Brunswick','New Jersey','US'),(1700,'2004 Charade Rd','98199','Seattle','Washington','US'),(1800,'147 Spadina Ave','M5V 2L7','Toronto','Ontario','CA'),(1900,'6092 Boxwood St','YSW 9T2','Whitehorse','Yukon','CA'),(2000,'40-5-12 Laogianggen','190518','Beijing',NULL,'CN'),(2100,'1298 Vileparle (E)','490231','Bombay','Maharashtra','IN'),(2200,'12-98 Victoria Street','2901','Sydney','New South Wales','AU'),(2300,'198 Clementi North','540198','Singapore',NULL,'SG'),(2400,'8204 Arthur St',NULL,'London',NULL,'UK'),(2500,'Magdalen Centre, The Oxford Science Park','OX9 9ZB','Oxford','Oxford','UK'),(2600,'9702 Chester Road','09629850293','Stretford','Manchester','UK'),(2700,'Schwanthalerstr. 7031','80925','Munich','Bavaria','DE'),(2800,'Rua Frei Caneca 1360 ','01307-002','Sao Paulo','Sao Paulo','BR'),(2900,'20 Rue des Corps-Saints','1730','Geneva','Geneve','CH'),(3000,'Murtenstrasse 921','3095','Bern','BE','CH'),(3100,'Pieter Breughelstraat 837','3029SK','Utrecht','Utrecht','NL'),(3200,'Mariano Escobedo 9991','11932','Mexico City','Distrito Federal,','MX');
 98 
 99 /*!40101 SET SQL_MODE=@OLD_SQL_MODE */;
100 /*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;
101 /*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;
102 /*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;

数据库myemployees

　　1、查询工资最低的员工信息：last_name,salary

　　　　#(1)查询最低的工资

　　　　　　select min(salary)

　　　　　　from employees

　　　　#(2)查询last_name,salary,要求salary=(1)

　　　　　　select last_name,salary

　　　　　　from employees

　　　　　　where salary = (

　　　　　　　　　　select min(salary)

　　　　　　　　　　from employees

　　　　　　);

　　2、查询平均工资最低的部门信息

　　　　#方法一：

　　　　#(1)各部门的平均工资

　　　　　　select avg(salary),department_id

　　　　　　from employees

　　　　　　group by department_id;

　　　　#(2)查询(1)结果上的最低平均工资

　　　　　　select min(ag)

　　　　　　from (

　　　　　　select avg(salary),department_id

　　　　　 from employees

　　　　　　group by department_id

　　　　　　);

　　　　#(3)查询哪个部门的平均工资=(2)

　　　　　　select avg(salary),department_id

　　　　　　from employees

　　　　　　group by department_id

　　　　　　having avg(salary)=(

　　　　　　select min(ag)

　　　　　　from (

　　　　　　select avg(salary),department_id

　　　　　　from employees

　　　　　　group by department_id

　　　　　　　　　　)

　　　　　　);

　　　　#(4)查询部门信息

　　　　　　select d.*

　　　　　　from department d

　　　　　　from d.department_id = (

　　　　　　　　select avg(salary),department_id

　　　　　　from employees

　　　　　　group by department_id

　　　　　　having avg(salary)=(

　　　　　　select min(ag)

　　　　　　 from (

　　　　　　 select avg(salary),department_id

　　　　　　from employees

　　　　　　group by department_id

　　　　　　　　)

　　　　　　);

　　　　方法二：

　　　　　　#(1)求出平均工资最低的部门编号

　　　　　　select avg(salary),department_id

　　　　　　from employees

　　　　　　group by department_id

　　　　　　order by avg(salary)

　　　　　　limit 1;

　　　　　　#(2)查询部门信息

　　　　　　select *

　　　　　　from departments

　　　　　　where department_id = (

select department_id

　　　　　　from employees

　　　　　　 group by department_id

　　　　　　order by avg(salary)

　　　　　　limit 1

　　　　　　);

　　3、查询平均工资最低的部门信息和该部门的平均工资

select departments.*,ag

from departments
inner join (
　　select avg(salary) as ag,department_id
　　from employees
　　group by department_id
　　order by avg(salary)
　　limit 1
　　) as dep_infom
on departments.department_id = dep_infom.department_id
where departments.department_id = (
　　select department_id
　　from employees
　　group by department_id
　　order by avg(salary)
　　limit 1
);

　　4、查询平均工资最高的job信息

　　　　#(1)查询每个job的平均工资

　　　　　　select avg(salary),job_id

　　　　　　from employees

　　　　　　group by job_id;

　　　　#(2)查询最高的平均工资与最高工资对应的job_id

　　　　　　select max(ag),job_id

　　　　　　from (

　　　　　　　　select avg(salary) as ag,job_id

　　　　　　　　from employees

　　　　　　　　group by job_id

　　　　　　　　order by ag desc

　　　　　　)　as ag_emp

　　　　　　limit 1;

　　　　#(3)查询对应的job信息

　　　　　　select jobs.*

　　　　　　from jobs

　　　　　　inner join (

　　　　　　　　select max(ag),job_id

　　　　　　　　from (

　　　　　　　　select avg(salary) as ag,job_id

　　　　　　　　from employees

　　　　　　　　group by job_id

　　　　　　　　order by ag desc

　　　　　　)　as ag_emp

　　　　　　limit 1

　　　　　　);

　　　　#或

　　　　　　select *

　　　　　　from jobs

　　　　　　where job_id =(

select job_id

from employees

group by job_id

order by avg(salary)

limit1

);

　　5、查询平均工资高于公司平均工资的部门有哪些？

　　#(1)公司的平均工资

　　　　select avg(salary)

　　　　from employees;

　　#(2)每个部门的平均工资

　　　　select avg(salary),department_id

　　　　from employees

　　　　group by department_id;

　　#(3)筛选(2)结果集,满足平均工资>(1)

　　　　select avg(salary),department_id

　　　　from employees

　　　　group by department_id

　　　having avg(salary)>(

　　　　　　select avg(salary)

　　　　　　from employees

　　　　);

　　6、查询出公司中所有manager的详细信息。

　　#(1)查询所有manager的员工编号

　　　　select distinct manager_id

　　　　from employee

　　#(2)查询详细信息，满足manager_id=(1)

　　　　select *

　　　　from employees

　　　　where employee_id = any (

　　　　　　select distinct manager_id

　　　　　　from employees

　　　　);

　　7、各个部门中最高工资中最低的那个部门的最低工资是多少

　　　　#(1)查询各部门的最高工资最低的那个部门

　　　　select max(salary),department_id

　　　　from employees

　　　　group by department_id

　　　　order by max(salary) asc

　　　　limit 1;

　　　　#(2)查询(1)结果的那个部门的最低工资　　

　　　　　　select min(salary)，department_id

　　　　　　from employees

　　　　　　group by department_id

　　　　　　having department_id = (　　　　# =不能替换为in

15:30:04

select min(salary)，department_id from employees group by departmenrt_id having department_id in ( select department_id from employees group by department_id order by max(salary) asc limit 1 ) LIMIT 0, 50000

Error Code: 1235. This version of MySQL doesn't yet support 'LIMIT & IN/ALL/ANY/SOME subquery'

0.000 sec

　　　　select department_id

　　　　from employees

　　　　group by department_id

　　　　order by max(salary) asc

　　　　limit 1

);

#或

select min(salary),department_id

from employees

where department_id = (

　　　　select department_id

　　　　from employees

　　　　group by department_id

　　　　order by max(salary) asc

　　　　limit 1

);

　　8、查询平均工资最高的部门的manager的详细信息：last_name, department_id, email, salary

　　　　#(1)平均工资最高的部门编号

　　　　　　 select avg(salary),department_id

from employees

group by department_id

order by avg(salary) desc

limit 1;

#(2)将employees和departments连接查询，筛选条件是(1)

select last_name,d.department_id,email,salary

from employees e

inner join departments d

on d.manager_id = e.employee_id

where d.department_id = (

select avg(salary),department_id

from employees

group by department_id

order by avg(salary) desc

limit 1

);

查看全文

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原文地址：https://www.cnblogs.com/tan-y-q/p/10573048.html

97-98复习连接查询、子查询,子查询经典案例

SQL99语法：

1.内连接

语法：

特点：

表的顺序可以调换

内连接的结果=多表的交集

n表连接至少需要n-1个连接条件

分类：

2、外连接:

语法：

3、交叉连接

子查询

一、含义

分页查询：

一、应用场景

二、语法

子查询经典案例：

　　语法：

　　特点：

n表连接至少需要n-1个连接条件　　　　　

　　分类：

　　语法：

子查询　

　　一、含义

　　一、应用场景　