MySQL基础20题(续前面的20题)
写在前面
今天继续前面的20题之后的练习，数据都是一样的，可以直接使用，来看看你的sql功底降了没。
基础20题
#1.查询每个员⼯的姓名、邮箱、职位名称以及所在部⻔名称。
SELECT
CONCAT(last_name,first_name) as 姓名,
email,
job_title,
department_name
FROM
employees e
JOIN departments d ON e.department_id=d.department_id
JOIN jobs j ON e.job_id = j.job_id ;
#2.查询⽉薪最⾼的员⼯的姓名、职位名称以及⽉薪。
SELECT
CONCAT(last_name,first_name) as 姓名,
job_title,
salary
FROM
employees e
JOIN jobs j on e.job_id = j.job_id
WHERE salary = (SELECT MAX(salary) FROM employees);
#3.查询每个部⻔的平均⽉薪。
#注：如果某一部门没有员工不会显示
SELECT
department_name,
AVG(salary)
FROM
employees e
JOIN departments d ON e.department_id = d.department_id
GROUP BY
department_name;
#4.查询部⻔中员⼯⽉薪⾼于5000的所有员⼯的姓名、⽉薪以及所在部⻔名称。
SELECT
CONCAT(last_name,first_name) as 姓名,
salary,
department_name
FROM
employees e
JOIN departments d ON e.department_id = d.department_id
WHERE
salary > 5000;
#5.查询奖⾦率最⾼的员⼯的姓名、职位名称以及奖⾦率。
SELECT
CONCAT(last_name,first_name) as 姓名,
job_title,
commission_pct
FROM
employees e
JOIN jobs j ON e.job_id = j.job_id
WHERE
commission_pct = (SELECT MAX(commission_pct) FROM employees);
#6.查询每个职位的最⾼⽉薪和最低⽉薪。
SELECT
job_title,
MAX(salary),
MIN(salary)
FROM
employees e
JOIN jobs j ON e.job_id = j.job_id
GROUP BY
job_title;
#7.查询⼊职时间早于2000年的所有员⼯的姓名、⼊职⽇期以及职位名称。
SELECT
CONCAT(last_name,first_name) as 姓名,
hiredate,
job_title
FROM
employees e
JOIN jobs j on e.job_id = j.job_id
WHERE
YEAR(hiredate) < 2000;
#8.查询每个部⻔的员⼯⼈数。
SELECT
COUNT(*) as 人数,
department_name
FROM
employees e
JOIN departments d ON e.department_id = d.department_id
GROUP BY
department_name;
#9.查询在每个部⻔中⽉薪最⾼的员⼯的姓名、⽉薪以及部⻔名称。
#注：在使用in时可以使用（）将需要的列括起来查询
SELECT
CONCAT(e.last_name,e.first_name) as 姓名,
e.salary,
d.department_name
FROM
employees e JOIN departments d ON e.department_id = d.department_id
WHERE
(e.salary,d.department_id) in (
SELECT MAX(salary),department_id FROM employees GROUP BY department_id);
#10.查询⽉薪超过部⻔平均⽉薪的员⼯的姓名、⽉薪以及所在部⻔名称。
SELECT
CONCAT( e1.last_name, e1.first_name ) AS 姓名,
e1.salary,
d.department_name
FROM
employees e1
JOIN departments d ON e1.department_id = d.department_id
WHERE
e1.salary > ( SELECT AVG( e2.salary ) FROM employees e2 WHERE e1.department_id = e2.department_id);
#11.查询每个职位的员⼯⼈数。
SELECT
COUNT(*) as 人数,
job_title
FROM
employees e
JOIN jobs j ON e.job_id = j.job_id
GROUP BY
job_title;
#12.查询每个部⻔的最⾼⽉薪和最低⽉薪。
SELECT
department_name,
MAX(salary),
MIN(salary)
FROM
employees e
JOIN departments d ON e.department_id = d.department_id
GROUP BY
department_name;
#13.查询每个员⼯的姓名、邮箱、职位名称以及他们的上级领导的姓名。
SELECT
CONCAT(e1.last_name,e1.first_name) as 姓名,
e1.email,
j.job_title,
CONCAT(e2.last_name,e2.first_name) as 上级领导
FROM
employees e1
JOIN employees e2 ON e1.manager_id = e2.employee_id
JOIN jobs j ON e1.job_id = j.job_id;
#14.查询每个部⻔的员⼯平均奖⾦率。
SELECT
department_name,
AVG(commission_pct) as 平均奖金率
FROM
employees e
JOIN departments d ON e.department_id = d.department_id
GROUP BY
department_name;
#15.查询每个城市的员⼯⼈数。
SELECT
COUNT(*) as 人数,
city
FROM
employees e
JOIN departments d ON e.department_id = d.department_id
JOIN locations l ON d.location_id = l.location_id
GROUP BY
city;
#16.查询每个部⻔的职位种类数。
#注：使用distinct可以去重算种类数
SELECT
COUNT(DISTINCT job_id) as 种类数,
department_name
FROM
employees e
JOIN departments d ON e.department_id = d.department_id
GROUP BY
department_name;
#17.查询⼯资⾼于其职位平均⼯资的员⼯姓名、职位名称以及⽉薪。
SELECT
CONCAT(e1.last_name, e1.first_name ) AS 姓名,
j.job_title,
e1.salary
FROM
employees e1
JOIN jobs j ON e1.job_id = j.job_id
WHERE
e1.salary > (SELECT AVG(e2.salary) FROM employees e2 WHERE e1.job_id = e2.job_id);
#18.查询每个国家的员⼯⼈数。
SELECT
COUNT(DISTINCT employee_id) as 人数,
country_id
FROM
employees e
JOIN departments d ON e.department_id = d.department_id
JOIN locations l ON d.location_id = l.location_id
GROUP BY
country_id;
#19.查询没有领导的员⼯的姓名以及职位名称。
SELECT
CONCAT( last_name, first_name ) AS 姓名,
job_title
FROM
employees e
JOIN jobs j ON e.job_id = j.job_id
WHERE
manager_id is null ;
#20.查询job_id为"IT_PROG"的员⼯的姓名、职位名称以及⽉薪。
SELECT
CONCAT( last_name, first_name ) AS 姓名,
job_title,
salary
FROM
employees e
JOIN jobs j ON e.job_id = j.job_id
WHERE
e.job_id = 'IT_PROG';
好了，今天的分享结束了，答案仅供参考不代表最终答案，如果有更换的方法，欢迎在底下留言评论！