題目 Table: Employee +--------------+---------+ | Column Name | Type | +--------------+---------+ | id | int | | name | varchar | | salary | int | | departmentId | int | +--------------+---------+ id is the primary key column for this table. departmentId is a foreign key of the ID from the Department table. Each row of this table indicates the ID, name, and salary of an employee. It also...

題目 Table: Trips +-------------+----------+ | Column Name | Type | +-------------+----------+ | id | int | | client_id | int | | driver_id | int | | city_id | int | | status | enum | | request_at | date | +-------------+----------+ id is the primary key for this table. The table holds all taxi trips. Each trip has a unique id, while client_id and driver_id are foreign keys...

題目 Table: Employee +--------------+---------+ | Column Name | Type | +--------------+---------+ | id | int | | company | varchar | | salary | int | +--------------+---------+ id is the primary key column for this table. Each row of this table indicates the company and the salary of one employee. Write an SQL query to find the rows that contain the median salary of each company. While calculating the...

題目 Table: Numbers +-------------+------+ | Column Name | Type | +-------------+------+ | num | int | | frequency | int | +-------------+------+ num is the primary key for this table. Each row of this table shows the frequency of a number in the database. The median is the value separating the higher half from the lower half of a data sample. Write an SQL query to report the median...

題目 Table: Employee +-------------+------+ | Column Name | Type | +-------------+------+ | id | int | | month | int | | salary | int | +-------------+------+ (id, month) is the primary key for this table. Each row in the table indicates the salary of an employee in one month during the year 2020. Write an SQL query to calculate the cumulative salary summary for every employee in a...

題目 Table: Stadium +---------------+---------+ | Column Name | Type | +---------------+---------+ | id | int | | visit_date | date | | people | int | +---------------+---------+ visit_date is the primary key for this table. Each row of this table contains the visit date and visit id to the stadium with the number of people during the visit. No two rows will have the same visit_date, and as the...

題目 Table: Salary +-------------+------+ | Column Name | Type | +-------------+------+ | id | int | | employee_id | int | | amount | int | | pay_date | date | +-------------+------+ id is the primary key column for this table. Each row of this table indicates the salary of an employee in one month. employee_id is a foreign key from the Employee table. Table: Employee +---------------+------+ | Column...

題目 Table: Student +-------------+---------+ | Column Name | Type | +-------------+---------+ | name | varchar | | continent | varchar | +-------------+---------+ There is no primary key for this table. It may contain duplicate rows. Each row of this table indicates the name of a student and the continent they came from. A school has students from Asia, Europe, and America. Write an SQL query to pivot the continent...

題目 Table: Activity +--------------+---------+ | Column Name | Type | +--------------+---------+ | player_id | int | | device_id | int | | event_date | date | | games_played | int | +--------------+---------+ (player_id, event_date) is the primary key of this table. This table shows the activity of players of some games. Each row is a record of a player who logged in and played a number of games (possibly...

題目 Table: Spending +-------------+---------+ | Column Name | Type | +-------------+---------+ | user_id | int | | spend_date | date | | platform | enum | | amount | int | +-------------+---------+ The table logs the history of the spending of users that make purchases from an online shopping website that has a desktop and a mobile application. (user_id, spend_date, platform) is the primary key of this table. The...