IshaSQL
Foundations Track · Easy · 15 min
Find Customer Referee
Table: Customer +-------------+---------+ | Column Name | Type | +-------------+---------+ | id | int | | name | varchar | | referee_id | int | +------------...
Company labels are directional practice context, not official interview guidance.
Objective
Practice filtering through a IshaSQL-tagged business scenario.
Approach
Use this track to lock in clean query structure, basic filtering logic, and confidence with grouped output.
Company context
Company labels are directional practice context, not official interview guidance.
Table: Customer +-------------+---------+ | Column Name | Type | +-------------+---------+ | id | int | | name | varchar | | referee_id | int | +-------------+---------+ In SQL, id is the primary key column for this table. Each row of this table indicates the id of a customer, their name, and the id of the customer who referred them. Find the names of the customer that are either: referred by any customer with id != 2 . not referred by any customer. Return the result table in any order . The result format is in the following example. Example 1: Input: Customer table: +----+------+------------+ | id | name | referee_id | +----+------+------------+ | 1 | Will | null | | 2 | Jane | null | | 3 | Alex | 2 | | 4 | Bill | null | | 5 | Zack | 1 | | 6 | Mark | 2 | +----+------+------------+ Output: +------+ | name | +------+ | Will | | Jane | | Bill | | Zack | +------+
Customer
SQL workspace
Run queries against the protected question data, then submit once the result shape looks right.
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