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

LeetCode 175: Combine Two Tables

Problem Restatement We are given two tables: Person and Address . The Person table stores each person's ID, first name, and last name. The Address table stores address records. Each address belongs to a person through personId . We need to report this information for every person: firstName, lastName, city, state The important part is that every person must appear in the result, even if that person has no address....
leetcode sql database join left-join May 12, 2026
Practice › LeetCode › LeetCode (archived) › LeetCode 05xx ›

LeetCode 580: Count Student Number in Departments

Problem Restatement We are given two tables: Student and Department . Each student belongs to one department. We need to report every department name and the number of students majoring in that department. Departments with no students must still appear in the result with count 0 . The result should be ordered by student_number in descending order. If two departments have the same number of students, order them by dept_name...
leetcode sql left-join group-by aggregation May 11, 2026
Practice › LeetCode › LeetCode (archived) › LeetCode 05xx ›

LeetCode 577: Employee Bonus

Problem Restatement We are given two tables: Employee and Bonus . The task is to report each employee's name and bonus when the employee satisfies one of these conditions: The employee has a bonus less than 1000 . The employee has no bonus record. Return the result table in any order. The official problem describes this as reporting the name and bonus amount of each employee whose bonus is less...
leetcode sql left-join null May 11, 2026
Practice › LeetCode › LeetCode (archived) › LeetCode 01xx ›

LeetCode 183: Customers Who Never Order

Problem Restatement We are given two tables: Customers and Orders . Customers stores customer information. Column Type id int name varchar Orders stores order information. Column Type id int customerId int The customerId column in Orders refers to Customers.id . We need to find all customers who never placed an order. The result can be returned in any order. The official problem asks for all customers who never order anything....
leetcode sql database left-join anti-join May 10, 2026