Most Asked SQL Interview Questions in 2024

By Team foundit May 13, 2024

1. Explain SELECT statement

[{"selector":"#anim-e4ad0be4-083f-42e2-b675-a1a1a7950dc9","keyframes":{"opacity":[1,1]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-c7155ab2-05dd-4ff3-a883-742465aea8b4","keyframes":{"transform":["scale(3)","scale(1)"]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-9f826e5f-2b23-498c-8ba9-edd2bda498a3","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-ac858dbe-fd94-4ce9-a82d-9203bade60f4","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-dfa7dada-e333-463a-a169-62d28f6a67ef","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-681eb511-052a-4d1c-8e15-d9a1f0bc510b","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] What's the basic structure of a SELECT statement in SQL?

2. JOINs in SQL

[{"selector":"#anim-69f5a0e7-5403-40d7-8b02-d312af177121","keyframes":{"opacity":[1,1]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-603054f7-b10b-4eb3-9714-f5551c1d95e1","keyframes":{"transform":["scale(3)","scale(1)"]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-d2f6f748-2410-48cd-8e22-4b9cab2e2861","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-abb8b2b2-be22-4f81-871e-d37072e6b99f","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-9cafa731-56df-4cd9-9a42-49f69e2b343a","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-02d87a8e-e3cf-42a0-810d-7c1917ad23af","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] How do you join multiple tables in SQL? Explain different join types.

3. Filtering data with WHERE clause

[{"selector":"#anim-703597ca-a486-4e91-b951-ce7153b200d1","keyframes":{"opacity":[1,1]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-3694a4a6-ece1-436f-88ef-95c04262363d","keyframes":{"transform":["scale(3)","scale(1)"]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-21d6d84b-75f3-443c-9648-27c69fce4b2b","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-20e0d305-8e49-4369-a896-4c301fb6a5a0","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-e6a88335-1fab-4e77-9bfe-141727a9baf0","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-94ed07f1-040c-4008-bb6b-5e5d9537b901","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] How do you filter data based on specific conditions using WHERE clause?

4. Grouping data with GROUP BY

[{"selector":"#anim-2e8fe2e3-fe9c-4d6c-9855-1d6eca878a7d","keyframes":{"opacity":[1,1]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-818e1b5b-d718-4888-b52e-32aea95832f7","keyframes":{"transform":["scale(3)","scale(1)"]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-b20c27b0-9d0e-4b3d-8fde-a2525f313485","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-e3cd5b1d-9d3f-4be2-acd8-78fc2281f0d2","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-553c1269-6cc4-4177-8ccf-3ebbbfc7394e","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-eb80cdba-b3b6-4063-b493-85060cfebd3d","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] How to group data and apply aggregate functions (COUNT, SUM, AVG) using GROUP BY?

5. Ordering data with ORDER BY

[{"selector":"#anim-bd3033ed-b239-42f5-950a-54a6a5ae8b31","keyframes":{"opacity":[1,1]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-85b36562-cd32-4b20-a2cf-c4197e79ac6a","keyframes":{"transform":["scale(3)","scale(1)"]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-15f5be72-6de7-49bc-af0b-8e10c509b57f","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-a3b0626c-0671-4a88-881d-d7244a141e85","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-ce7d3ab2-23cb-454b-a80c-cc3e8e6e0a76","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-84443ff4-929e-4177-bf8e-a6cfcfe1c0db","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] How to sort data in ascending or descending order using ORDER BY?

6. Subqueries in SQL

[{"selector":"#anim-1ab9637a-b2dc-4ed6-b64b-86db7e0d1cde","keyframes":{"opacity":[1,1]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-0ff959a3-c824-40ff-a3a3-c19541669efd","keyframes":{"transform":["scale(3)","scale(1)"]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-a0e0f058-74f1-4c97-a63e-97f7e8c414fd","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-141a1e45-aee2-4cf2-a61a-8b22965889cf","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-1c429333-f209-4c1e-a992-64ce003a6d47","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-7ab85f54-a9e1-4db0-820e-66799a3a9e19","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] What are subqueries and how can you use them in SQL statements?

7. Explain UNION and UNION ALL

[{"selector":"#anim-9f4db0a8-4ed1-459b-9dbe-210e757a951c","keyframes":{"opacity":[1,1]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-6dff6632-5e85-418e-a4d8-c91c4afe07a6","keyframes":{"transform":["scale(3)","scale(1)"]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-bb5831b0-a3e5-427f-90f9-c1a5bbb14a3f","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-b6c6f572-2d3c-4ccb-a38e-9744f25d6442","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-11308212-5261-4ed9-91bb-d5ba2e2a096c","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-c282d4d8-1ea9-4bce-a086-387a8da6f702","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] Differentiate between UNION and UNION ALL for combining data sets.

8. Aggregate Functions

[{"selector":"#anim-475682c3-1254-4074-b97e-94c7a1913663","keyframes":{"opacity":[1,1]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-f13198d4-d7a0-48b8-9dc9-3d576b37559e","keyframes":{"transform":["scale(3)","scale(1)"]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-6b92e625-b80b-43f2-bd22-1ed29ab3876b","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-04a2562c-5d8a-43d3-a7ab-635f2b4245ed","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-3c904c02-cef9-469e-b26e-f9b592247b37","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-ca7c0f09-461a-4edb-a6f7-58039e47213b","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] List two common aggregate functions used in SQL.

9. Write a query to find the top 5 customers

[{"selector":"#anim-418e6e6d-1e43-4f14-9ee9-af421ce67d72","keyframes":{"opacity":[1,1]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-406a7d82-ecd7-442e-a426-de7e22e1463d","keyframes":{"transform":["scale(3)","scale(1)"]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-bc03b79f-5656-4c89-8ece-700d7dd946bb","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-f825eee8-026a-48d3-9b89-06662c0d0e30","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-3c4f98e8-8ffc-49e7-a2ad-a0784a537716","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-16de1024-fd9a-405e-bec8-52921e583edc","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] Can you write a SQL query to find the top 5 customers based on their purchase history?

10. SQL Injection

[{"selector":"#anim-469b98f6-e6b3-4840-958b-4c34a35e1002","keyframes":{"opacity":[1,1]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-357d774a-2e4f-414e-a583-378e15f19b4d","keyframes":{"transform":["scale(3)","scale(1)"]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-690f611d-99a1-4c58-a9f5-1d8d87cca34e","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-c3761ad0-450e-4fc7-905d-0d16b9c54acb","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-91905a9a-8bf0-49a1-9584-d1878100b60d","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-8cf7ed7f-3b15-4966-aa38-e6b25949c3d7","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] How can you prevent SQL injection attacks?

Ready To Apply

[{"selector":"#anim-ede332f7-5af6-42ed-b7c5-a26691a5f1ff","keyframes":{"opacity":[1,1]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-18dc3248-c0f6-4d7d-8c95-d18e7eb538af","keyframes":{"transform":["scale(3)","scale(1)"]},"delay":10,"duration":1500,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-b8eb2bb3-8f96-4b3b-92e6-29b582f34af4","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-686679bc-6853-4c9b-b64e-0ffda0d38a70","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] [{"selector":"#anim-432ed356-a30f-48c6-a084-4a8b577e76ca","keyframes":{"opacity":[0,1]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"both"}] [{"selector":"#anim-af27375d-38ee-4aa2-90ea-35b508838c13","keyframes":{"transform":["scale(0.3333333333333333)","scale(1)"]},"delay":0,"duration":2000,"easing":"cubic-bezier(.3,0,.55,1)","fill":"forwards"}] Don't wait! Update your resume and register at foundit to apply for these exciting opportunities. Register Now