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Practice › LeetCode › LeetCode (archived) › LeetCode 01xx ›

LeetCode 197: Rising Temperature

Problem Restatement We are given a table named Weather . Schema: Column Type id int recordDate date temperature int The id column is unique. There are no duplicate recordDate values. We need to find the id of every date where the temperature is higher than the temperature on the previous day. Example table: id recordDate temperature 1 2015-01-01 10 2 2015-01-02 25 3 2015-01-03 20 4 2015-01-04 30 Expected output:...
leetcode sql mysql database self-join May 12, 2026
Practice › LeetCode › LeetCode (archived) › LeetCode 01xx ›

LeetCode 196: Delete Duplicate Emails

Problem Restatement We are given a table named Person . Schema: Column Type id int email varchar The id column is unique. Some rows may contain duplicate email addresses. We need to delete duplicate rows so that: Every email appears only once. The row with the smallest id is kept. All other duplicate rows are removed. Example table: id email 1 john@example.com 2 bob@example.com 3 john@example.com After deletion: id email...
leetcode sql mysql delete self-join May 12, 2026
Practice › LeetCode › LeetCode (archived) › LeetCode 06xx ›

LeetCode 614: Second Degree Follower

Problem Restatement We are given a table called Follow . Each row means one user follows another user. Column Type Meaning followee varchar The user being followed follower varchar The user who follows followee The pair (followee, follower) is the primary key. A second-degree follower is a user who: follows at least one user is followed by at least one user We need to return every second-degree follower and the...
leetcode sql self-join group-by database May 12, 2026
Practice › LeetCode › LeetCode (archived) › LeetCode 06xx ›

LeetCode 613: Shortest Distance in a Line

Problem Restatement We are given a table called Point . Each row stores one point on the X-axis. Column Type Meaning x int Position of the point on the X-axis The column x is the primary key, so every point is unique. We need to find the shortest distance between any two points. The official problem asks for the minimum distance between any two points from the Point table. Input...
leetcode sql self-join window-function database May 12, 2026
Practice › LeetCode › LeetCode (archived) › LeetCode 06xx ›

LeetCode 612: Shortest Distance in a Plane

Problem Restatement We are given a table called Point2D . Each row represents one point in a 2D plane. Column Type Meaning x decimal x-coordinate y decimal y-coordinate We need to find the shortest Euclidean distance between any two distinct points. The result should contain one column: Column Meaning shortest Minimum distance between any pair of points The final answer should be rounded to two decimal places. The official problem...
leetcode sql geometry self-join math database May 12, 2026
Practice › LeetCode › LeetCode (archived) › LeetCode 05xx ›

LeetCode 570: Managers with at Least 5 Direct Reports

Problem Restatement We are given an Employee table. Column Type Meaning id int Employee id name varchar Employee name department varchar Department name managerId int Id of this employee's manager If managerId is NULL , the employee does not report to anyone. We need to find managers who have at least five direct reports. A direct report means an employee whose managerId is equal to that manager's id . Return...
leetcode sql database group-by self-join May 11, 2026
Practice › LeetCode › LeetCode (archived) › LeetCode 06xx ›

LeetCode 603: Consecutive Available Seats

Problem Restatement We are given a table called Cinema . Each row tells us whether a seat is free or occupied. Column Type Meaning seat_id int Seat id free bool 1 means free, 0 means occupied We need to return all free seats that are part of at least one consecutive pair of free seats. The result should be ordered by seat_id . The problem note says seat_id is auto-incremented,...
leetcode sql self-join window-function database May 11, 2026
Practice › LeetCode › LeetCode (archived) › LeetCode 05xx ›

LeetCode 579: Find Cumulative Salary of an Employee

Problem Restatement We are given an Employee table that stores each employee's salary for different months. For each employee and each month they worked, we need to calculate the sum of that month's salary and the salaries from the previous two months. However, we must not include the employee's most recent month in the output. The result should be ordered by id in ascending order, then by month in descending...
leetcode sql window-function self-join aggregation May 11, 2026
Practice › LeetCode › LeetCode (archived) › LeetCode 01xx ›

LeetCode 181: Employees Earning More Than Their Managers

Problem Restatement We are given a table named Employee . Column Type id int name varchar salary int managerId int Each row stores one employee. The managerId column points to the id of that employee's manager. We need to return the names of employees who earn more than their managers. The result can be returned in any order. The official problem asks for employees whose salary is greater than their...
leetcode sql database self-join May 10, 2026
Practice › LeetCode › LeetCode (archived) › LeetCode 01xx ›

LeetCode 180: Consecutive Numbers

Problem Restatement We are given a table named Logs . Column Type id int num varchar The column id is the primary key. It is an auto-increment column starting from 1 . We need to find every number that appears at least three times consecutively. The result can be returned in any order. The output column should be named ConsecutiveNums . The official statement asks for all numbers that appear...
leetcode sql database self-join window-function May 10, 2026