SQL/LeetCode

문제 Table: Tweets +----------------+---------+ | Column Name | Type | +----------------+---------+ | tweet_id | int | | content | varchar | +----------------+---------+ tweet_id is the primary key (column with unique values) for this table. This table contains all the tweets in a social media app. Write a solution to find the IDs of the invalid tweets. The tweet is invalid if the number of charac..

문제 Table: Users +----------------+---------+ | Column Name | Type | +----------------+---------+ | user_id | int | | name | varchar | +----------------+---------+ user_id is the primary key (column with unique values) for this table. This table contains the ID and the name of the user. The name consists of only lowercase and uppercase characters. Write a solution to fix the names so that only th..

문제 Table: Activity +----------------+---------+ | Column Name | Type | +----------------+---------+ | machine_id | int | | process_id | int | | activity_type | enum | | timestamp | float | +----------------+---------+ The table shows the user activities for a factory website. (machine_id, process_id, activity_type) is the primary key (combination of columns with unique values) of this table. mac..

문제 Table: Users +-------------+---------+ | Column Name | Type | +-------------+---------+ | user_id | int | | user_name | varchar | +-------------+---------+ user_id is the primary key (column with unique values) for this table. Each row of this table contains the name and the id of a user. Table: Register +-------------+---------+ | Column Name | Type | +-------------+---------+ | contest_id |..

문제 Table: Users +--------------+---------+ | Column Name | Type | +--------------+---------+ | account | int | | name | varchar | +--------------+---------+ account is the primary key (column with unique values) for this table. Each row of this table contains the account number of each user in the bank. There will be no two users having the same name in the table. Table: Transactions +----------..

문제 Table: Visits +-------------+---------+ | Column Name | Type | +-------------+---------+ | visit_id | int | | customer_id | int | +-------------+---------+ visit_id is the column with unique values for this table. This table contains information about the customers who visited the mall. Table: Transactions +----------------+---------+ | Column Name | Type | +----------------+---------+ | tran..

문제 Table: Patients +--------------+---------+ | Column Name | Type | +--------------+---------+ | patient_id | int | | patient_name | varchar | | conditions | varchar | +--------------+---------+ patient_id is the primary key (column with unique values) for this table. 'conditions' contains 0 or more code separated by spaces. This table contains information of the patients in the hospital. Write..

문제 Table: Users +---------------+---------+ | Column Name | Type | +---------------+---------+ | user_id | int | | name | varchar | | mail | varchar | +---------------+---------+ user_id is the primary key (column with unique values) for this table. This table contains information of the users signed up in a website. Some e-mails are invalid. Write a solution to find the users who have valid ema..

문제 Table Activities: +-------------+---------+ | Column Name | Type | +-------------+---------+ | sell_date | date | | product | varchar | +-------------+---------+ There is no primary key (column with unique values) for this table. It may contain duplicates. Each row of this table contains the product name and the date it was sold in a market. Write a solution to find for each date the number o..

문제 Table: Users +---------------+---------+ | Column Name | Type | +---------------+---------+ | id | int | | name | varchar | +---------------+---------+ id is the column with unique values for this table. name is the name of the user. Table: Rides +---------------+---------+ | Column Name | Type | +---------------+---------+ | id | int | | user_id | int | | distance | int | +---------------+--..