Thread by @swapnakpanda

SQL Interview Questions (S3)

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This is the 3rd one in this series. Check the 2nd one 👇

https://twitter.com/swapnakpanda/status/1457594773951303680?s=20

Disclaimer:

• The questions covered here are mostly conceptual
• I never claim only these type of questions are/should be asked during interviews
• For interviews, you should have fundamentals strong. And you should be able to provide solutions to practical problems.

Series: 3️⃣
Level: Beginner
Topics:

1️⃣ DDL
2️⃣ DML
3️⃣ Sequence
4️⃣ Synonym
5️⃣ Trigger

1️⃣ DDL

✪ Give some examples of DDL commands
✪ Write syntax of creating a table
✪ How to specify default value for a column?
✪ How to specify a foreign key?
✪ How to specify a unique key?
✪ How to specify multiple columns as primary key?

✪ What are different constraints you can add to a column while creating a table?
✪ How to create a copy of a table? (both structure and, data)
✪ You have 'n' tables and asked to create a separate table which will contain few columns from these tables being data copied.

✪ What is SELECT INTO used for? (SQL Server)
✪ Difference between ALTER and RENAME
✪ Can a previously nullable column be altered to a NOT NULL column? If yes, how?

2️⃣ DML

✪ What are different syntax for inserting records into a table?
✪ What is the syntax to insert multiple records at a time?
✪ Explain how DML operations are performed on a View. Or, View is for SELECT queries only?

3️⃣ Sequence

✪ What is a sequence? Why is it useful?
✪ Write syntax for creating a syntax.
✪ What does a sequence return?
✪ How to fetch the value from a sequence?
✪ Can a sequence definition be changed once after creating? What is the syntax?

✪ What details we can pass while creating a sequence?
✪ What details of a sequence can be changed?
✪ How to reset a sequence?

4️⃣ Synonym

✪ What is a synonym?
✪ Why is synonym useful?
✪ For which all database objects, a synonym can be created?
✪ Write syntax for creating a synonym.
✪ What is a public and private synonym?

✪ Can a private synonym be changed to public and vice versa later?
✪ How to change definition of a synonym?
✪ What all details can be changed for a synonym?

5️⃣ Trigger

✪ What is a trigger?
✪ Describe how a trigger functions.
✪ Write syntax for creating a trigger.
✪ What are different types of triggers?
✪ Give examples of some events (operations) for which a trigger can be run.

✪ Describe a BEFORE trigger.
✪ Describe an AFTER trigger.
✪ Describe an INSTEAD OF trigger.
✪ What can an INSTEAD OF trigger do?
✪ How to use a view for all DML operations using a trigger? Describe.

The next series would cover,

1️⃣ More on SELECT Query
2️⃣ More on Operators
3️⃣ Custom Functions
4️⃣ Stored Procedures

👇 is one of the creative content I have made. It’s a cheat sheet on creation of arrays in JavaScript. Do check and share your feedbacks.

https://twitter.com/swapnakpanda/status/1461307946743205891