3个常考的SQL数据分析题（含数据和代码）
DROP TABLE IF EXISTS employee;
CREATE TABLE employee(
employee_id VARCHAR(8),
employee_name VARCHAR(8),
employee_salary INT(8),
department VARCHAR(8)
)
ENGINE = InnoDB
DEFAULT CHARSET = utf8;
INSERT INTO
employee (employee_id,employee_name,employee_salary,department)
VALUE ('a001','Bob',7000,'b1')
,('a002','Jack',9000,'b1')
,('a003','Alice',8000,'b2')
,('a004','Ben',5000,'b2')
,('a005','Candy',4000,'b2')
,('a006','Allen',5000,'b2')
,('a007','Linda',10000,'b3');
DROP TABLE IF EXISTS department;
CREATE TABLE department(
department_id VARCHAR(8),
department_name VARCHAR(8)
)
ENGINE = InnoDB
DEFAULT CHARSET = utf8;
INSERT INTO
department (department_id,department_name)
VALUE ('b1','Sales')
,('b2','IT')
,('b3','Product');
SELECT a.employee_id
,a.employee_name
,a.employee_salary
,b.department_id
FROM
(
SELECT *
,RANK() OVER (PARTITION BY department ORDER BY employee_salary DESC) AS ranking
FROM employee
) AS a
INNER JOIN department AS b
ON a.department = b.department_id
WHERE a.ranking = 2;
数据导入的代码如下：DROP TABLE IF EXISTS login_info;
CREATE TABLE login_info(
user_id VARCHAR(8),
login_time DATE
)
ENGINE = InnoDB
DEFAULT CHARSET = utf8;
INSERT INTO
login_info (user_id,login_time)
VALUE ('a001','2021-01-01')
,('b001','2021-01-01')
,('a001','2021-01-03')
,('a001','2021-01-06')
,('a001','2021-01-07')
,('b001','2021-01-07')
,('a001','2021-01-08')
,('a001','2021-01-09')
,('b001','2021-01-09')
,('b001','2021-01-10')
,('b001','2021-01-15')
,('a001','2021-01-16')
,('a001','2021-01-18')
,('a001','2021-01-19')
,('b001','2021-01-20')
,('a001','2021-01-23');
SELECT user_id
,login_time
,LEAD(login_time,1) OVER (PARTITION BY user_id ORDER BY login_time) AS next_login_time
FROM login_info;
SELECT a.user_id
,COUNT(*) AS num
FROM
(
SELECT user_id
,login_time
,LEAD(login_time,1) OVER (PARTITION BY user_id ORDER BY login_time) AS next_login_time
FROM login_info
) AS a
WHERE TIMESTAMPDIFF(DAY, login_time, next_login_time) < 5
GROUP BY user_id;
DROP TABLE IF EXISTS purchase_channel;
CREATE TABLE purchase_channel(
user_id VARCHAR(8),
channel VARCHAR(8),
purchase_date DATE,
purchase_amount INT(8)
)
ENGINE = InnoDB
DEFAULT CHARSET = utf8;
INSERT INTO
purchase_channel (user_id,channel,purchase_date,purchase_amount)
VALUE ('a001','app','2021-03-14',200)
,('a001','web','2021-03-14',100)
,('a002','app','2021-03-14',400)
,('a001','web','2021-03-15',3000)
,('a002','app','2021-03-15',900)
,('a003','app','2021-03-15',1000);
SELECT purchase_date
,channel
,SUM(sum_amount) sum_amount
,SUM(total_users) total_users
FROM
(
SELECT purchase_date
,MIN(channel) channel
,SUM(purchase_amount) sum_amount
,COUNT(DISTINCT user_id) total_users
FROM purchase_channel
GROUP BY purchase_date
,user_id
HAVING COUNT(DISTINCT channel) = 1 UNION
SELECT purchase_date
,'both' channel
,SUM(purchase_amount) sum_amount
,COUNT(DISTINCT user_id) total_users
FROM purchase_channel
GROUP BY purchase_date
,user_id
HAVING COUNT(DISTINCT channel) > 1
) c
GROUP BY purchase_date
,channel;
SELECT t1.purchase_date
,t1.channel
,t2.sum_amount
,t2.total_users
FROM
(
SELECT DISTINCT a.purchase_date
,b.channel
FROM purchase_channel a,
(
SELECT "app" AS channel
UNION
SELECT "web" AS channel
UNION
SELECT "both" AS channel
) b
) t1
LEFT JOIN
(
SELECT
purchase_date,
channel,
SUM(sum_amount) sum_amount,
SUM(total_users) total_users
FROM (
SELECT purchase_date
,MIN(channel) channel
,SUM(purchase_amount) sum_amount
,COUNT(DISTINCT user_id) total_users
FROM purchase_channel
GROUP BY purchase_date,user_id
HAVING COUNT(DISTINCT channel) = 1
UNION
SELECT purchase_date
,'both' channel
,SUM(purchase_amount) sum_amount
,COUNT(DISTINCT user_id) total_users
FROM purchase_channel
GROUP BY purchase_date,user_id
HAVING COUNT(DISTINCT channel) > 1
)c GROUP BY purchase_date, channel
) t2
ON t1.purchase_date = t2.purchase_date AND t1.channel = t2.channel;
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