实战演练——数据表查询操作

实战演练——数据表查询操作

– 创建一个名叫dty_db的数据库

CREATE DATABASE dty_db;

– 选择dty_db数据库

USE dty_db;

– 创建一个数据表dept

CREATE TABLE dept
(
d_no INT PRIMARY KEY AUTO_INCREMENT,
d_name VARCHAR(50),
d_location VARCHAR(100)
)ENGINE=InnoDB;

– 创建一个数据表employee

CREATE TABLE employee
(
e_no INT PRIMARY KEY,
e_name VARCHAR(100) NOT NULL,
e_gender CHAR(2) NOT NULL,
dept_no INT NOT NULL,
e_job VARCHAR(100) NOT NULL,
e_salary SMALLINT NOT NULL,
hireDate DATE,
CONSTRAINT fk_employee_dept FOREIGN KEY(dept_no) REFERENCES dept(d_no)
);

– 向dept表插入数据

INSERT INTO dept
VALUES (10,'ACCOUNTING','ShangHai'),
(20,'RESEARCH','BeiJing'),
(30,'SALES','ShenZhen'),
(40,'OPERATIONS','FuJian');

– 向employee表中插入数据

INSERT INTO employee
VALUES (1001,'SMITH','m',20,'CLERK',800,'2005-11-12'),
(1002,'ALLEN','f',30,'SALESMAN',1600,'2003-05-12'),
(1003,'WARD','f',30,'SALESMAN',1250,'2003-05-12'),
(1004,'JONES','m',20,'MANAGER',2975,'1998-05-18'),
(1005,'MARTIN','m',30,'SALESMAN',1250,'2001-06-12'),
(1006,'BLAKE','f',30,'MANAGER',2850,'1997-02-15'),
(1007,'CLARK','m',10,'MANAGER',2450,'2002-09-12'),
(1008,'SCOTT','m',20,'ANALYST',3000,'2003-05-12'),
(1009,'KING','f',10,'PRESIDENT',5000,'1995-01-01'),
(1010,'TURNER','f',30,'SALESMAN',1500,'1997-10-01'),
(1011,'ADAMS','m',20,'CLERK',1100,'1999-10-05'),
(1012,'JAMES','m',20,'CLERK',950,'2008-06-15');

– 在employee表中，查询所有记录的e_no、e_name、e_salary字段值

SELECT e_no, e_name, e_salary FROM employee;

– 在employee表中，查询dept_no等于10和20的所有记录

SELECT * FROM employee WHERE dept_no IN(10,20);

– 在employee表中查询工资为800-2500的员工信息

SELECT * FROM employee WHERE e_salary BETWEEN 800 AND 2500;

– 在employee表中查询部门编号为20的部门中员工的信息

SELECT * FROM employee WHERE dept_no = 20;

– 在employee表中查询每个部门最高工资的员工信息

SELECT dept_no, MAX(e_salary) FROM employee GROUP BY dept_no;

– 查询员工BLAKE所在部门和部门所在地

SELECT d_no, d_location FROM dept WHERE d_no=(SELECT dept_no FROM employee WHERE e_name='BLAKE');

– 使用连接查询，查询所有员工的部门和部门信息

SELECT e_no, e_name, dept_no, d_name, d_location FROM employee, dept WHERE dept.d_no=employee.dept_no;

– 在employee表中计算每个部门各有多少名员工

SELECT dept_no,COUNT(*) FROM employee GROUP BY dept_no;

– 在employee表中计算不同类型职工的总工资数

SELECT e_job,SUM(e_salary) FROM employee GROUP BY e_job;

– 在employee表中计算不同部门的平均工资

SELECT dept_no, AVG(e_salary) FROM employee GROUP BY dept_no;

– 在employee表中查询工资低于1500的员工信息

SELECT * FROM employee WHERE e_salary < 1500;

– 在employee表中将查询记录先按部门编号由高到低排序，再按员工工资由高到低排列

SELECT e_name,dept_no, e_salary FROM employee ORDER BY dept_no DESC, e_salary DESC;

– 在employee表中查询员工姓名以字母‘A’或‘S’开头的员工信息

SELECT * FROM employee WHERE e_name REGEXP'^[as]';

– 在employee表中查询到目前为止，工龄大于等于15的员工信息

SELECT * FROM employee where YEAR(CURDATE())-YEAR(hireDate) >= 15;