原文上傳到百度文庫,如今發現word文檔不便於閱讀,所以更改寫爲markdown形式。

1 建庫和建表：

1.1 創建數據庫：

create database lsydb1 default character set utf8;
use lsydb1;

1.2 創建表（dept）：

create table dept (deptno int primary key, dname nvarchar(30), loc nvarchar(30)) default character set utf8;

1.3 創建表（emp）：

create table emp ( empno int primary key, ename nvarchar(30), job nvarchar(30), mgr int , hiredate datetime, sal decimal(6.2), comm decimal(6.2), deptno int ,foreign key(deptno) references dept(deptno)) default character set utf8;

1.4 向dept表插入數據（先插dept再插emp）：

insert into dept (deptno, dname, loc) 
values (10, 'ACCOUNTING', 'NEW YORK'),
(20, 'RESEARCH', 'DALLAS'),
(30, 'SALES', 'CHICAGO'),
(40, 'OPERATIONS', 'BOSTON');

dept表如下：

+--------+------------+----------+ 
| deptno | dname      | loc      | 
+--------+------------+----------+ 
|     10 | ACCOUNTING | NEW YORK | 
|     20 | RESEARCH   | DALLAS   | 
|     30 | SALES      | CHICAGO  | 
|     40 | OPERATIONS | BOSTON   | 
+--------+------------+----------+

1.5 向emp表插入數據

insert into emp (empno,ename,job,mgr,hiredate,sal,comm,deptno) values (7369,'SMITH','CLERK',7902,'1980-12-17',800.00,NULL,20);
insert into emp (empno,ename,job,mgr,hiredate,sal,comm,deptno) values (7499,'ALLEN','SALESMAN',7698,'1981-2-20',1600,300,30);
insert into emp (empno,ename,job,mgr,hiredate,sal,comm,deptno) values ( 7521, 'WARD', 'SALESMAN', 7698, '1981-2-22', 1250, 500, 30);
insert into emp (empno,ename,job,mgr,hiredate,sal,comm,deptno) values ( 7566, 'JONES', 'MANAGER', 7839, '1981-4-2', 2975, null, 20);
insert into emp (empno,ename,job,mgr,hiredate,sal,comm,deptno) values ( 7654, 'MARTIN', 'SALESMAN', 7698, '1981-9-28', 1250, 1400, 30);
insert into emp (empno,ename,job,mgr,hiredate,sal,comm,deptno) values ( 7698, 'BLAKE', 'MANAGER', 7839, '1981-5-1', 2850, NULL, 30);
insert into emp (empno,ename,job,mgr,hiredate,sal,comm,deptno) values ( 7782, 'CLARK', 'MANAGER', 7839, '1981-6-9', 2450, NULL, 10);
insert into emp (empno,ename,job,mgr,hiredate,sal,comm,deptno) values ( 7788, 'SCOTT', 'ANALYST', 7566, '1987-4-19', 3000, NULL, 20);
insert into emp (empno,ename,job,mgr,hiredate,sal,comm,deptno) values ( 7839, 'KING', 'PRESIDENT', NULL, '1981-11-17', 5000, NULL, 10);
insert into emp (empno,ename,job,mgr,hiredate,sal,comm,deptno) values ( 7844, 'TURNER', 'SALESMAN', 7698, '1981-9-8', 1500, 0, 30);
insert into emp (empno,ename,job,mgr,hiredate,sal,comm,deptno) values (7876, 'ADAMS', 'CLERK', 7788, '1987-5-23', 1100, NULL, 20);
insert into emp (empno,ename,job,mgr,hiredate,sal,comm,deptno) values (7900, 'JAMES', 'CLERK', 7698, '1981-12-3', 950, NULL, 30);
insert into emp (empno,ename,job,mgr,hiredate,sal,comm,deptno) values ( 7902, 'FORD', 'ANALYST', 7566, '1981-12-3', 3000, NULL, 20);
insert into emp (empno,ename,job,mgr,hiredate,sal,comm,deptno) values (7934, 'MILLER', 'CLERK', 7782, '1982-1-23', 1300, NULL, 10);

emp表：

+-------+--------+-----------+------+---------------------+------+------+--------+ 
| empno | ename  | job       | mgr  | hiredate            | sal  | comm | deptno | 
+-------+--------+-----------+------+---------------------+------+------+--------+ 
|  7369 | SMITH  | CLERK     | 7902 | 1980-12-17 00:00:00 |  800 | NULL |     20 | 
|  7499 | ALLEN  | SALESMAN  | 7698 | 1981-02-20 00:00:00 | 1600 |  300 |     30 | 
|  7521 | WARD   | SALESMAN  | 7698 | 1981-02-22 00:00:00 | 1250 |  500 |     30 | 
|  7566 | JONES  | MANAGER   | 7839 | 1981-04-02 00:00:00 | 2975 | NULL |     20 | 
|  7654 | MARTIN | SALESMAN  | 7698 | 1981-09-28 00:00:00 | 1250 | 1400 |     30 | 
|  7698 | BLAKE  | MANAGER   | 7839 | 1981-05-01 00:00:00 | 2850 | NULL |     30 | 
|  7782 | CLARK  | MANAGER   | 7839 | 1981-06-09 00:00:00 | 2450 | NULL |     10 | 
|  7788 | SCOTT  | ANALYST   | 7566 | 1987-04-19 00:00:00 | 3000 | NULL |     20 | 
|  7839 | KING   | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000 | NULL |     10 | 
|  7844 | TURNER | SALESMAN  | 7698 | 1981-09-08 00:00:00 | 1500 |    0 |     30 | 
|  7876 | ADAMS  | CLERK     | 7788 | 1987-05-23 00:00:00 | 1100 | NULL |     20 | 
|  7900 | JAMES  | CLERK     | 7698 | 1981-12-03 00:00:00 |  950 | NULL |     30 | 
|  7902 | FORD   | ANALYST   | 7566 | 1981-12-03 00:00:00 | 3000 | NULL |     20 | 
|  7934 | MILLER | CLERK     | 7782 | 1982-01-23 00:00:00 | 1300 | NULL |     10 | 
+-------+--------+-----------+------+---------------------+------+------+--------+

2 基本查詢操作：

2.1 如何查詢工資在2000到2500的員工情況

select * from emp where sal> 2000 and sal < 2500;
select * from emp where  sal between 2000 and 2500;

between是取兩邊的包括2000和2500.

2.2 模糊查詢：

顯示首字母爲S的員工的姓名和工資

select ename ,sal from emp where ename like “s%”;

2.3 顯示empno爲123,345,800..的僱員情況。

使用 in關鍵字效率更高。

Select * from emp where emono in (123,345,800);

3 複雜查詢操作：

3.1 顯示員工最低和最高工資。

 select ename ,sal from emp where sal>= ( select max(sal) from emp) or sal<= (select min(sal) from emp);

3.2 顯示員工平均工資和總工資

select sum(sal),avg(sal) from emp;

3.3 顯示高於平均工作僱員的姓名和工資,並顯示平均工資。

select ename ,sal ,(select avg(sal) from emp) from emp where sal > (select avg(sal) from emp);

3.4 顯示員工人數：

select count(ename) from emp;

group by:用於查詢的結果分組統計。
having by:用於限制分組顯示結果。

3.5 顯示每個部門的平均工資和最高工資

 mysql> select deptno,avg(sal) as "每個部門的平均工資" ,max(sal) as "每個部門的最高工資" from emp group by deptno;

結果下圖：

+--------+-----------------------------+-----------------------------+ 
| deptno | 每個部門的平均工資          | 每個部門的最高工資          | 
+--------+-----------------------------+-----------------------------+ 
|     10 |                   2916.6667 |                        5000 | 
|     20 |                   2175.0000 |                        3000 | 
|     30 |                   1566.6667 |                        2850 | 
+--------+-----------------------------+-----------------------------+

3.6 顯示每個部門的沒中崗位的平均工資和最低工資：

select avg(sal),min(sal) ,deptno,job from emp group by deptno,job;

結果圖：

+-----------+----------+--------+-----------+ 
| avg(sal)  | min(sal) | deptno | job       | 
+-----------+----------+--------+-----------+ 
| 1300.0000 |     1300 |     10 | CLERK     | 
| 2450.0000 |     2450 |     10 | MANAGER   | 
| 5000.0000 |     5000 |     10 | PRESIDENT | 
| 3000.0000 |     3000 |     20 | ANALYST   | 
|  950.0000 |      800 |     20 | CLERK     | 
| 2975.0000 |     2975 |     20 | MANAGER   | 
|  950.0000 |      950 |     30 | CLERK     | 
| 2850.0000 |     2850 |     30 | MANAGER   | 
| 1400.0000 |     1250 |     30 | SALESMAN  |

3.7 顯示平均工資低於2000的部門和他的平均工資

（having往往和group by結合使用，可以對分組查詢結果進行篩選）

 select avg(sal)  ,deptno from emp group  by deptno having avg(sal) < 2000 ;

4 複雜查詢（多表）

4.1 顯示僱員的名字和部門的地點：

select emp.ename,dept.loc from emp,dept where emp.deptno=dept.deptno and dept.dname="sales";

結果：

+--------+---------+ 
| ename  | loc     | 
+--------+---------+ 
| ALLEN  | CHICAGO | 
| WARD   | CHICAGO | 
| MARTIN | CHICAGO | 
| BLAKE  | CHICAGO | 
| TURNER | CHICAGO | 
| JAMES  | CHICAGO | 
+--------+---------+

4.2 顯示部門號爲10的部門名，員工名和工資。

Select dept.dname,emp.ename,emp.sal from dept,emp where emp.deptno=dept.deptno and dept.deptno=10;

結果：

+------------+--------+------+ 
| dname      | ename  | sal  | 
+------------+--------+------+ 
| ACCOUNTING | CLARK  | 2450 | 
| ACCOUNTING | KING   | 5000 | 
| ACCOUNTING | MILLER | 1300 | 
+------------+--------+------+

4.3 顯示僱員名，僱員工資及所在部門的名字，並按部門排序。

 select emp.ename,emp.sal,dept.dname from emp,dept where emp.deptno=dept.deptno order by dept.dname;

結果：

+--------+------+------------+ 
| ename  | sal  | dname      | 
+--------+------+------------+ 
| CLARK  | 2450 | ACCOUNTING | 
| KING   | 5000 | ACCOUNTING | 
| MILLER | 1300 | ACCOUNTING | 
| SMITH  |  800 | RESEARCH   | 
| JONES  | 2975 | RESEARCH   | 
| SCOTT  | 3000 | RESEARCH   | 
| ADAMS  | 1100 | RESEARCH   | 
| FORD   | 3000 | RESEARCH   | 
| ALLEN  | 1600 | SALES      | 
| WARD   | 1250 | SALES      | 
| MARTIN | 1250 | SALES      | 
| BLAKE  | 2850 | SALES      | 
| TURNER | 1500 | SALES      | 
| JAMES  |  950 | SALES      | 
+--------+------+------------+

自連接：同一張表的連接查詢。

4.4 顯示某員工的上級領導的姓名，比如“FORD”的上級。

 select ename from emp where empno=(select mgr from emp where ename="ford");
 ```

圖：

```shell
+-------+ 
| ename | 
+-------+ 
| JONES | 
+-------+ 




<div class="se-preview-section-delimiter"></div>

4.5 顯示公司每個員工名字和他上級的名字。

4.5.1 自連接。

select a.ename,b.ename from emp a,emp b where b.empno=a.mgr ; 




<div class="se-preview-section-delimiter"></div>

結果:

+--------+-------+ 
| ename  | ename | 
+--------+-------+ 
| SMITH  | FORD  | 
| ALLEN  | BLAKE | 
| WARD   | BLAKE | 
| JONES  | KING  | 
| MARTIN | BLAKE | 
| BLAKE  | KING  | 
| CLARK  | KING  | 
| SCOTT  | JONES | 
| TURNER | BLAKE | 
| ADAMS  | SCOTT | 
| JAMES  | BLAKE | 
| FORD   | JONES | 
| MILLER | CLARK | 




<div class="se-preview-section-delimiter"></div>

4.5.2 外鏈接（左和右）

4.6 顯示與SMITH同一部門的所有員工。(單行子查詢)

select * from emp where deptno=(select deptno from emp where ename="SMITH");
select * from emp where deptno in (select deptno from emp where ename="SMITH");

4.7 顯示和部門10的工作相同的僱員名字，崗位，工資和部門號。（多行子查詢）

（部門包括10）

select ename,job,sal,deptno from emp where job in (select distinct job from emp where deptno=10); 




<div class="se-preview-section-delimiter"></div>

圖：

+--------+-----------+------+--------+ 
| ename  | job       | sal  | deptno | 
+--------+-----------+------+--------+ 
| SMITH  | CLERK     |  800 |     20 | 
| JONES  | MANAGER   | 2975 |     20 | 
| BLAKE  | MANAGER   | 2850 |     30 | 
| CLARK  | MANAGER   | 2450 |     10 | 
| KING   | PRESIDENT | 5000 |     10 | 
| ADAMS  | CLERK     | 1100 |     20 | 
| JAMES  | CLERK     |  950 |     30 | 
| MILLER | CLERK     | 1300 |     10 | 
+--------+-----------+------+--------+ 




<div class="se-preview-section-delimiter"></div>

（部門不包括10）

select ename,job,sal,deptno from emp where job in (select distinct job from emp where deptno=10) and deptno <> 10; 




<div class="se-preview-section-delimiter"></div>

圖：

+-------+---------+------+--------+ 
| ename | job     | sal  | deptno | 
+-------+---------+------+--------+ 
| SMITH | CLERK   |  800 |     20 | 
| JONES | MANAGER | 2975 |     20 | 
| BLAKE | MANAGER | 2850 |     30 | 
| ADAMS | CLERK   | 1100 |     20 | 
| JAMES | CLERK   |  950 |     30 | 




<div class="se-preview-section-delimiter"></div>

在from語句中使用子查詢。

4.8 顯示高於部門平均工資的員工信息。

 select emp.ename,emp.sal,emp.deptno,tmp.myavg  from emp,(select avg(sal) myavg ,deptno from emp group by deptno )  tmp where emp.sal>myavg and tmp.deptno=emp.deptno;
 ```
圖：




<div class="se-preview-section-delimiter"></div>

```sql
+-------+------+--------+-----------+ 
| ename | sal  | deptno | myavg     | 
+-------+------+--------+-----------+ 
| KING  | 5000 |     10 | 2916.6667 | 
| JONES | 2975 |     20 | 2175.0000 | 
| SCOTT | 3000 |     20 | 2175.0000 | 
| FORD  | 3000 |     20 | 2175.0000 | 
| ALLEN | 1600 |     30 | 1566.6667 | 
| BLAKE | 2850 |     30 | 1566.6667 | 
+-------+------+--------+-----------+ 
 ```
##  4.9 顯示第5到第10入職僱員（按時間的先後）
```sql
select * from emp order by hiredate asc  limit 4,7; 




<div class="se-preview-section-delimiter"></div>

圖：

+-------+--------+-----------+------+---------------------+------+------+--------+ 
| empno | ename  | job       | mgr  | hiredate            | sal  | comm | deptno | 
+-------+--------+-----------+------+---------------------+------+------+--------+ 
|  7698 | BLAKE  | MANAGER   | 7839 | 1981-05-01 00:00:00 | 2850 | NULL |     30 | 
|  7782 | CLARK  | MANAGER   | 7839 | 1981-06-09 00:00:00 | 2450 | NULL |     10 | 
|  7844 | TURNER | SALESMAN  | 7698 | 1981-09-08 00:00:00 | 1500 |    0 |     30 | 
|  7654 | MARTIN | SALESMAN  | 7698 | 1981-09-28 00:00:00 | 1250 | 1400 |     30 | 
|  7839 | KING   | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000 | NULL |     10 | 
|  7902 | FORD   | ANALYST   | 7566 | 1981-12-03 00:00:00 | 3000 | NULL |     20 | 
|  7900 | JAMES  | CLERK     | 7698 | 1981-12-03 00:00:00 |  950 | NULL |     30 | 




<div class="se-preview-section-delimiter"></div>

4.10 左外連接和右外連接

（左外連接）：左邊的表記錄全部顯示，如果沒有匹配記錄就顯示NULL
（右外連接）：右邊的表記錄全部顯示，如果沒有匹配記錄就顯示NULL
例子如下圖：

4.11 顯示公司每位員工和他的上級名字，沒有上級的名字也要顯示。

select a.ename,b.ename  from emp a left join emp b on  a.mgr=b.empno;




<div class="se-preview-section-delimiter"></div>

圖：

+--------+-------+ 
| ename  | ename | 
+--------+-------+ 
| SMITH  | FORD  | 
| ALLEN  | BLAKE | 
| WARD   | BLAKE | 
| JONES  | KING  | 
| MARTIN | BLAKE | 
| BLAKE  | KING  | 
| CLARK  | KING  | 
| SCOTT  | JONES | 
| KING   | NULL  | 
| TURNER | BLAKE | 
| ADAMS  | SCOTT | 
| JAMES  | BLAKE | 
| FORD   | JONES | 
| MILLER | CLARK | 
+--------+-------+ 




<div class="se-preview-section-delimiter"></div>

5 題目看下圖：

5.1 先創建goods表。

create table goods (goodsId nvarchar(50) primary key, goodsName nvarchar(80) not null, unitPrice decimal(8,2) check(unitPrice > 0), category nvarchar(3) check(catagory in("食物","日用品")), provider nvarchar(50)) default character set utf8;




<div class="se-preview-section-delimiter"></div>

圖：

+-----------+--------------+------+-----+---------+-------+ 
| Field     | Type         | Null | Key | Default | Extra | 
+-----------+--------------+------+-----+---------+-------+ 
| goodsId   | varchar(50)  | NO   | PRI | NULL    |       | 
| goodsName | varchar(80)  | NO   |     | NULL    |       | 
| unitPrice | decimal(8,2) | YES  |     | NULL    |       | 
| category  | varchar(3)   | YES  |     | NULL    |       | 
| provider  | varchar(50)  | YES  |     | NULL    |       | 




<div class="se-preview-section-delimiter"></div>

5.2 創建customer表：

create table customer  (customerId nvarchar(50) primary key, custName nvarchar(50) not null, address nvarchar(100), email nvarchar(100) unique, sex nchar(1) default "男" check(sex in("男","女")) , cardId nvarchar(18) ) default character set utf8;




<div class="se-preview-section-delimiter"></div>

圖：

+------------+--------------+------+-----+---------+-------+ 
| Field      | Type         | Null | Key | Default | Extra | 
+------------+--------------+------+-----+---------+-------+ 
| customerId | varchar(50)  | NO   | PRI | NULL    |       | 
| custName   | varchar(50)  | NO   |     | NULL    |       | 
| address    | varchar(100) | YES  |     | NULL    |       | 
| email      | varchar(100) | YES  | UNI | NULL    |       | 
| sex        | char(1)      | YES  |     | 男      |       | 
| cardId     | varchar(18)  | YES  |     | NULL    |       | 
+------------+--------------+------+-----+---------+-------+ 




<div class="se-preview-section-delimiter"></div>

5.3 創建purchase表。

create table purchase ( 
customerId nvarchar(50) , 
goodsId nvarchar(50) , 
nums int check(nums>0) , 
CONSTRAINT `purchase_fk_customerId` FOREIGN KEY (`customerId`) REFERENCES `customer` (`customerId`), 
CONSTRAINT `purchase_fk_goodsId'` FOREIGN KEY (`goodsId`) REFERENCES `goods` (`goodsId`)) default character set utf8;




<div class="se-preview-section-delimiter"></div>

圖：

+------------+-------------+------+-----+---------+-------+ 
| Field      | Type        | Null | Key | Default | Extra | 
+------------+-------------+------+-----+---------+-------+ 
| customerId | varchar(50) | YES  | MUL | NULL    |       | 
| goodsId    | varchar(50) | YES  | MUL | NULL    |       | 
| nums       | int(11)     | YES  |     | NULL    |       | 
+------------+-------------+------+-----+---------+-------+

[原創]轉載請註明來自韓順平的java入門到精通中serversql筆記(包括emp表和dept表,linux的mysql版)

韓順平的java入門到精通中serversql筆記,包括emp表和dept表 linux的mysql版