Linkedin Interview Questions (7+ Questions)

We need to find customers without orders. We have two tables, customers and orders. These tables are connected through customer ID column. Our job here is to find customers who have never placed a single order, but at the same time they exist in the customers table. We are more interested in LEFT JOIN since we want all rows from the left table to stay. A LEFT JOIN keeps all rows from the left table, even if there is no matching row in the right table. The missing values just become null. Then we add the LEFT JOIN operator in between, and ON keyword that indicates which common columns were used to combine the tables. In our case, it's customer ID. We proceed with WHERE clause that filters the results. We build the condition to check if order ID is null. We pick this specific column because if a customer has at least one order, their order ID will be a real number after the LEFT JOIN. Finally, we sort everything by customer name in ascending order or alphabetically.

Detailed Explanation for SQL Query to Retrieve Customer Names, Total Spending, and Customer Tier

In the context of SQL interview questions, a commonly asked problem involves retrieving customer names along with their total spending and classifying them into different tiers based on their spendi...

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How to Calculate Yearly Total Sales, Previous Year's Total Sales, and Sales Growth Percentage with SQL

When you're faced with the task of calculating yearly total sales, the previous year's sales, and the growth percentage in SQL, it's essential to use efficient querying techniques to achieve a...

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SELECT
candidate_id
FROM
candidates
WHERE
skill IN ('Python', 'Tableau', 'PostgreSQL')
GROUP BY
candidate_id
HAVING
COUNT(DISTINCT skill) = 3
ORDER BY
candidate_id ASC;

SELECT
COUNT(DISTINCT company_id) AS duplicate_companies
FROM
(
SELECT
company_id,
title,
description
FROM
job_listings
GROUP BY
company_id,
title,
description
HAVING
COUNT(job_id) > 1
) AS duplicates;

Airbnb hosts over 6 million listings across 220+ countries with 150 million users. QA testing of property booking APIs requires comprehensive validation of search algorithms, availability checking, booking workflows, and review systems to ensure seamless travel experiences....

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Stripe is a leading payment processing platform handling billions of transactions. QA testing of payment APIs requires comprehensive validation of endpoints, status codes, response times, and data integrity to ensure secure and reliable financial transactions....

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