SQL基础语句练习

Posted 2022-04-14 Weikun Xing

文章目录

• 创建数据库数据表
• • test_db数据库
  •  学生表：stu
  •  雇员表：emp
  •  部门表：dept
• 练习题

创建数据库数据表

test_db数据库

create database test_db;
use test_db;

数据都是造的，不必当真

 学生表：stu

字段名称	字段类型	说明
sid	char(6)	学生学号
sname	varchar(50)	学生姓名
age	int	学生年龄
gender	varchar(50)	学生性别

CREATE TABLE stu (
	sid	CHAR(6),
	sname		VARCHAR(50),
	age		INT,
	gender	VARCHAR(50)
);

插入数据

INSERT INTO stu VALUES('S_1001', 'liuYi', 35, 'male');
INSERT INTO stu VALUES('S_1002', 'chenEr', 15, 'female');
INSERT INTO stu VALUES('S_1003', 'zhangSan', 95, 'male');
INSERT INTO stu VALUES('S_1004', 'liSi', 65, 'female');
INSERT INTO stu VALUES('S_1005', 'wangWu', 55, 'male');
INSERT INTO stu VALUES('S_1006', 'zhaoLiu', 75, 'female');
INSERT INTO stu VALUES('S_1007', 'sunQi', 25, 'male');
INSERT INTO stu VALUES('S_1008', 'zhouBa', 45, 'female');
INSERT INTO stu VALUES('S_1009', 'wuJiu', 85, 'male');
INSERT INTO stu VALUES('S_1010', 'zhengShi', 5, 'female');
INSERT INTO stu VALUES('S_1011', 'xxx', NULL, NULL);

 雇员表：emp

字段名称	字段类型	说明
empno	int	员工编号
ename	varchar(50)	员工姓名
job	varchar(50)	员工工作
mgr	int	领导编号
hiredate	date	入职日期
sal	decimal(7,2)	月薪
comm	decimal(7,2)	奖金
deptno	int	部分编号

CREATE TABLE emp(
	empno		INT,
	ename		VARCHAR(50),
	job		VARCHAR(50),
	mgr		INT,
	hiredate	DATE,
	sal		DECIMAL(7,2),
	comm		decimal(7,2),
	deptno		INT
) ;

INSERT INTO emp values(7369,'SMITH','CLERK',7902,'1980-12-17',800,NULL,20);
INSERT INTO emp values(7499,'ALLEN','SALESMAN',7698,'1981-02-20',1600,300,30);
INSERT INTO emp values(7521,'WARD','SALESMAN',7698,'1981-02-22',1250,500,30);
INSERT INTO emp values(7566,'JONES','MANAGER',7839,'1981-04-02',2975,NULL,20);
INSERT INTO emp values(7654,'MARTIN','SALESMAN',7698,'1981-09-28',1250,1400,30);
INSERT INTO emp values(7698,'BLAKE','MANAGER',7839,'1981-05-01',2850,NULL,30);
INSERT INTO emp values(7782,'CLARK','MANAGER',7839,'1981-06-09',2450,NULL,10);
INSERT INTO emp values(7788,'SCOTT','ANALYST',7566,'1987-04-19',3000,NULL,20);
INSERT INTO emp values(7839,'KING','PRESIDENT',NULL,'1981-11-17',5000,NULL,10);
INSERT INTO emp values(7844,'TURNER','SALESMAN',7698,'1981-09-08',1500,0,30);
INSERT INTO emp values(7876,'ADAMS','CLERK',7788,'1987-05-23',1100,NULL,20);
INSERT INTO emp values(7900,'JAMES','CLERK',7698,'1981-12-03',950,NULL,30);
INSERT INTO emp values(7902,'FORD','ANALYST',7566,'1981-12-03',3000,NULL,20);
INSERT INTO emp values(7934,'MILLER','CLERK',7782,'1982-01-23',1300,NULL,10);

 部门表：dept

字段名称	字段类型	说明
deptno	int	部分编码
dname	varchar(50)	部分名称
loc	varchar(50)	部分所在地点

CREATE TABLE dept(
	deptno		INT,
	dname		varchar(14),
	loc		varchar(13)
);

INSERT INTO dept values(10, 'ACCOUNTING', 'NEW YORK');
INSERT INTO dept values(20, 'RESEARCH', 'DALLAS');
INSERT INTO dept values(30, 'SALES', 'CHICAGO');
INSERT INTO dept values(40, 'OPERATIONS', 'BOSTON');

练习题

1、查询性别为女，并且年龄小于50的记录

select * from stu where gender like 'female' and age<50;

2、查询学号为S_1001，或者姓名为liSi的记录

select * from stu where sid like 'S_1001' or sname like 'liSi';

3、查询学号为S_1001，S_1002，S_1003的记录

select * from stu where sid in ('S_1001','S_1002','S_1003');

4、查询学号不是S_1001，S_1002，S_1003的记录

select * from stu where sid not in ('S_1001','S_1002','S_1003');

5、查询年龄为null的记录

select * from stu where age is null;

6、查询年龄在20到40之间的学生记录

select * from stu where age between 20 and 40;

7、查询性别非男的学生记录

select * from stu where gender not like 'male';
select * from stu where gender<>'male';

8、查询姓名不为null的学生记录

select * from stu where sname is not null;

9、查询姓名由5个字母构成的学生记录

select * from stu where sname like '_____';

10、查询姓名由5个字母构成，并且第5个字母为“i”的学生记录

select * from stu where sname like '____i';

11、查询姓名以“z”开头的学生记录

select * from stu where sname like 'z%';

12、查询姓名中第2个字母为“i”的学生记录

select * from stu where sname like '_i%';

13、查询姓名中包含“a”字母的学生记录

select * from stu where sname like '%a%';

14、查询所有学生记录，按年龄升序排序

select * from stu order by age;

15、查询所有学生记录，按年龄降序排序

select * from stu order by age desc;

16、查询所有雇员，按月薪降序排序，如果月薪相同时，按编号升序排序

select * from emp order by sal desc,empno;

17、查询emp表中月薪大于2500的人数：

select count(*) as 'sal>2500' from emp where sal>2500;

18、统计月薪与佣金之和大于2500元的人数：

select count(*) as 'sal+comm>2500' from emp where sal+ifnull(comm,0)>2500;

19、查询有佣金的人数，以及有领导的人数：

SELECT COUNT(comm), COUNT(mgr) FROM emp;

20、查询所有雇员月薪和，以及所有雇员佣金和：

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

21、查询所有雇员月薪+佣金和：

select sum(sal+ifnull(comm,0)) from emp;

22、统计所有员工平均工资：

select sum(sal)/count(sal) from emp;
select avg(sal) from emp;

23、查询每个部门的部门编号和每个部门的工资和：

select deptno,sum(sal) from emp group by deptno;

24、查询每个部门的部门编号以及每个部门的人数：

select deptno,count(empno) from emp group by deptno;

25、查询每个部门的部门编号以及每个部门工资大于1500的人数：

select deptno,count(sal) from emp where sal>1500 group by deptno;

26、查询工资总和大于9000的部门编号以及工资和：

select deptno,sum(sal) from emp group by deptno having sum(sal)>9000;

27、查询5行记录，起始行从0开始

select * from emp limit 0,5;

28、查询10行记录，起始行从3开始

select * from emp limit 3,10;

这些题是基础题，提升可以去力扣或者牛客上刷题