LeetCode 197: Rising Temperature
A clear explanation of the Rising Temperature SQL problem using a self join and date comparison.
Tag
Sql
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LeetCode 196: Delete Duplicate Emails
A clear explanation of the Delete Duplicate Emails SQL problem using DELETE with a self join.
LeetCode 175: Combine Two Tables
A clear SQL guide for solving Combine Two Tables using LEFT JOIN.
LeetCode 627: Swap Salary
A SQL update solution for swapping all m and f values in the Salary table using a single statement.
LeetCode 626: Exchange Seats
A SQL solution for swapping every pair of adjacent student seats while leaving the final seat unchanged when the row count is odd.
LeetCode 620: Not Boring Movies
A SQL guide for filtering movies with odd IDs and non-boring descriptions, then sorting by rating.
LeetCode 619: Biggest Single Number
A SQL guide for finding the largest number that appears exactly once in a table.
LeetCode 618: Students Report By Geography
A SQL guide for pivoting rows into columns using ranking and conditional aggregation.
LeetCode 615: Average Salary: Departments VS Company
A SQL guide for comparing each department's monthly average salary against the company's monthly average salary.
LeetCode 614: Second Degree Follower
A SQL guide for finding users who both follow someone and have followers, then counting how many followers they have.
LeetCode 613: Shortest Distance in a Line
A SQL guide for finding the minimum distance between any two unique points on the X-axis.
LeetCode 612: Shortest Distance in a Plane
A SQL guide for finding the minimum Euclidean distance between any two points in a 2D plane.
LeetCode 610: Triangle Judgement
A SQL guide for checking whether three side lengths can form a valid triangle using the triangle inequality.
LeetCode 608: Tree Node
A SQL guide for classifying binary tree nodes as Root, Inner, or Leaf based on parent-child relationships.
LeetCode 607: Sales Person
A SQL guide for finding salespeople who never had an order related to the company named RED.
LeetCode 603: Consecutive Available Seats
A SQL guide for finding all cinema seats that are free and adjacent to at least one other free seat.
LeetCode 602: Friend Requests II: Who Has the Most Friends
A SQL guide for counting friendships from both requester and accepter sides, then returning the user with the most friends.
LeetCode 601: Human Traffic of Stadium
A SQL guide for finding stadium records that belong to runs of at least three consecutive ids where each row has at least 100 people.
LeetCode 512: Game Play Analysis II
A clear explanation of finding the first device used by each player using SQL aggregation and a join.
LeetCode 511: Game Play Analysis I
A clear explanation of finding each player's first login date using SQL aggregation.
LeetCode 597: Friend Requests I: Overall Acceptance Rate
A clear SQL guide for computing the overall friend request acceptance rate with duplicate pairs counted once.
LeetCode 596: Classes With at Least 5 Students
A clear SQL guide for finding classes that have at least five students.
LeetCode 595: Big Countries
A clear SQL guide for finding countries with either large area or large population.
LeetCode 586: Customer Placing the Largest Number of Orders
A clear SQL guide for finding the customer who placed the most orders.
LeetCode 585: Investments in 2016
A clear SQL guide for summing 2016 investments for policies with repeated 2015 investment values and unique locations.
LeetCode 584: Find Customer Referee
A clear SQL guide for selecting customers who were not referred by customer 2, including customers with no referee.
LeetCode 580: Count Student Number in Departments
A clear SQL guide for counting students in every department, including departments with zero students.
LeetCode 579: Find Cumulative Salary of an Employee
A clear SQL guide for computing each employee's 3-month cumulative salary while excluding their most recent month.
LeetCode 578: Get Highest Answer Rate Question
A clear SQL guide for finding the question with the highest answer rate from survey logs.
LeetCode 577: Employee Bonus
A clear SQL guide for finding employees whose bonus is less than 1000 or missing.
LeetCode 574: Winning Candidate
A clear explanation of Winning Candidate using SQL aggregation to count votes and return the candidate with the most votes.
LeetCode 571: Find Median Given Frequency of Numbers
A clear explanation of Find Median Given Frequency of Numbers using cumulative frequency and SQL window functions.
LeetCode 570: Managers with at Least 5 Direct Reports
A clear explanation of Managers with at Least 5 Direct Reports using grouping and a self join.
LeetCode 569: Median Employee Salary
A clear explanation of Median Employee Salary using SQL window functions to rank employees inside each company.
LeetCode 550: Game Play Analysis IV
A clear explanation of calculating the fraction of players who logged in again the day after their first login.
LeetCode 534: Game Play Analysis III
A clear explanation of computing cumulative games played per player and date using SQL window functions.
LeetCode 262: Trips and Users
A clear explanation of the Trips and Users SQL problem using joins, filtering, grouping, and conditional aggregation.
LeetCode 185: Department Top Three Salaries
A clear SQL solution for finding employees whose salaries are in the top three unique salary levels within their department.
LeetCode 184: Department Highest Salary
A clear SQL solution for finding every employee who earns the highest salary in their department.
LeetCode 183: Customers Who Never Order
A clear SQL solution for finding customers who have no matching rows in the Orders table.
LeetCode 182: Duplicate Emails
A clear SQL solution for reporting email values that appear more than once in the Person table.
LeetCode 181: Employees Earning More Than Their Managers
A clear SQL solution for finding employees whose salary is greater than their manager's salary using a self join.
LeetCode 180: Consecutive Numbers
A clear SQL solution for finding numbers that appear at least three times consecutively in the Logs table.
LeetCode 178: Rank Scores
A clear SQL solution for ranking scores with dense ranking, where ties share the same rank and no rank numbers are skipped.
LeetCode 177: Nth Highest Salary
A clear SQL solution for finding the nth highest distinct salary from the Employee table.
LeetCode 176: Second Highest Salary
A clear SQL solution for finding the second highest distinct salary from the Employee table.