Are you preparing for a SQL interview?
Here are some essential SQL concepts to review:
𝐁𝐚𝐬𝐢𝐜 𝐒𝐐𝐋 𝐂𝐨𝐧𝐜𝐞𝐩𝐭𝐬:
1. What is SQL, and why is it important in data analytics?
2. Explain the difference between
INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL OUTER JOIN. 3. What is the difference between
WHERE and HAVING clauses? 4. How do you use
GROUP BY and HAVING in a query? 5. Write a query to find duplicate records in a table.
6. How do you retrieve unique values from a table using SQL?
7. Explain the use of aggregate functions like
COUNT(), SUM(), AVG(), MIN(), and MAX(). 8. What is the purpose of a
DISTINCT keyword in SQL? 𝐈𝐧𝐭𝐞𝐫𝐦𝐞𝐝𝐢𝐚𝐭𝐞 𝐒𝐐𝐋:
1. Write a query to find the second-highest salary from an employee table.
2. What are subqueries and how do you use them?
3. What is a Common Table Expression (CTE)? Give an example of when to use it.
4. Explain window functions like
ROW_NUMBER(), RANK(), and DENSE_RANK(). 5. How do you combine results of two queries using
UNION and UNION ALL? 6. What are indexes in SQL, and how do they improve query performance?
7. Write a query to calculate the total sales for each month using
GROUP BY. 𝐀𝐝𝐯𝐚𝐧𝐜𝐞𝐝 𝐒𝐐𝐋:
1. How do you optimize a slow-running SQL query?
2. What are views in SQL, and when would you use them?
3. What is the difference between a stored procedure and a function in SQL?
4. Explain the difference between
TRUNCATE, DELETE, and DROP commands. 5. What are windowing functions, and how are they used in analytics?
6. How do you use
PARTITION BY and ORDER BY in window functions? 7. How do you handle NULL values in SQL, and what functions help with that (e.g.,
COALESCE, ISNULL)?Here you can find essential SQL Interview Resources👇
https://t.me/mysqldata
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Hope it helps :)