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75+ SQL Interview Questions

⇩

 Level: Beginner to Medium
Topics:

➊ Introduction to RDBMS
➋ Normalisation
➌ Introduction to SQL
➍ Tables and Fields
➎ Constraints
➏ DDL
➐ DML & DQL
➑ Joins
➊ Introduction to RDBMS

➀ What is a Database?
➁ What are different types of Databases?
➂ What is DBMS?
➃ What is difference between Database and DBMS?
➄ What is RDBMS?
➅ Which are popular RDBMS vendors?
➆ What is ACID property in Database?
➋ Normalisation

➀ What is Normalisation?
➁ Why is Normalisation necessary?
➂ What are the disadvantages of not performing Normalisation?
➃ What are different Normal Forms (NF)?
➄ What is Denormalisation?
➌ Introduction to SQL

➀ What is SQL?
➁ What is the use of SQL?
➂ Is SQL a programming language?
➃ What are the different parts of SQL?
Or,
➄ Group SQL commands in different parts.
➅ What is DDL?
➆ What is DML?
➇ What is DQL?
➈ What is DCL?
➉ What is TCL?
➍ Tables and Fields

➀ What is a Table?
➁ What is a field in a Table?
➂ Write a SQL command to create a Table.
➃ How to change the name of a Table?
➄ How to truncate a table?
➅ How to drop a table?
➎ Constraints

➀ What is a constraint?
➁ What are different levels of constraints?
➂ Give examples of various constraints?
➃ What is a primary key?
➄ What is a unique key?
➅ Difference between a primary key and a unique key.
➆ What is a foreign key?
➇ What is NULL value?
➈ What is NOT NULL constraint?
➉ Is blank space or Zero (0) same as NULL?
➏ DDL

➀ Give some examples of DDL commands
➁ Write the syntax of creating a table
➂ How to specify the default value for a column?
➃ How to specify a foreign key?
➄ How to specify a unique key?
➅ How to specify multiple columns as the primary key?
➆ What are different constraints you can add to a column while creating a table?
➇ How to create a copy of a table? (both structure and, data)
➈ You have 'n' tables and asked to create a separate table which will contain a few columns from these tables with data being copied.
➉ What is SELECT INTO used for? (In SQL Server)
➀➀ Difference between ALTER and RENAME
➀➁ Can a previously nullable column be altered to a NOT NULL column? If yes, explain the steps.
➐ DML & DQL

➀ How to insert rows into a table?
➁ What are different syntaxes for inserting records into a table?
➂ What is the syntax to insert multiple records at a time?
➃ How to update data in a table?
➄ How to delete a row in a table?
➅ Difference between DELETE and TRUNCATE?
➆ Explain how DML operations are performed on a View.
Or,
➇ Are Views used only for SELECT queries?
➈ How to fetch rows of a table?
➉ What is a query condition? How to write it in SQL?
➀➀ How to sort the fetched records?
➀➁ What is grouping? How to write in SQL?
➀➂ How to find how many records are being fetched?
➀➃ How to find the maximum and minimum value for a field in fetched records?
➀➄ How to sum values in a field for all records?
➑ Joins

➀ What is a join in SQL?
➁ What are the different types of joins?
➂ What is Inner Join?
➃ What is Left Outer Join?
➄ What is Right Outer Join?
➅ What is Full Outer Join?
➆ What is Cross Join?
➇ What is a Self Join?
➈ What is Equi Join?
➉ What is Natural Join?

➀➀ Given a query in Cross Join, convert it into an Inner Join.

➀➁ Given a query in Right Outer Join, convert it into a Left Outer Join.
➀➂ Convert an Inner Join into an Equi Join.
Or,
➀➃ What is required to convert an Inner Join into an Equi Join?

➀➄ What should be taken care of to improve the performance of queries containing Joins.
🚥 Disclaimer

⬘ The questions covered here are mostly conceptual

⬗ I never claim only these types 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.
Hey 👋

I am a Tech Educator and, Mentor from India 🇮🇳

I am sharing Tutorials, Tips, Techniques, Infographics, Cheat Sheets, Practice Questions, Project Ideas and Roadmaps on Web Development, DSA and, Databases.

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👩‍💻 75+ SQL Practice Questions

❍ Oracle
❍ MySQL
❍ SQL Server
❍ PostgreSQL
❍ SQLite

⇩

Topics covered:

➊ Table
➋ Constraints
➀ Primary Key
➁ Unique
➂ Not Null
➃ Default
➄ Check
➅ Foreign Key
➌ Insert, Update, Delete
➍ Select

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➀ Create a Table with a few fields by specifying their data types.

➁ Add a field to an existing table.

➂ Modify a field's data type of a table.

➃ Rename a field's name.

➄ Remove a field from a table.

➅ Rename a table's name.

➆ Drop a table.

➋ Constraints

➀ Primary Key
➁ Unique
➂ Not Null
➃ Default
➄ Check
➅ Foreign Key

➋.➀ Primary Key

➤ Create a Table with
➀ a single field as the primary key
➁ 2 or, more fields as the primary key
...

➤ Add a primary key to an existing table
➂ for a single field
➃ for 2 or, more fields
...
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30+ resources to learn

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❍ PL/SQL
❍ NoSQL

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➊.➀ freeCodeCamp

@mike_dane via @freeCodeCamp

➤ SQL Tutorial for

➊.➁ Web Dev Simplified (WDS)

@DevSimplified

➤ Learn SQL in 60

➊.➂ Programming with Mosh

@moshhamedani

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JavaScript First, Then React?
Or,
JavaScript ✛ React?

⇩

👩‍💻 Beginning Words

There are 3 approaches one can take to start React journey

➊ Complete JavaScript. Then, start React.

➋ Learn the essentials of JavaScript. Then, start React. Finally, learn advanced JavaScript.

➌ Start React. Learn JavaScript alongside.

💭 Why is this Thread?

⬘ JavaScript is a language while React is one JavaScript-based library.

⬗ Looking at the popularity of React, few people directly start learning React without much/prior knowledge of JavaScript. Is this a good idea?

⬙ Whichever approach you may take, it's important to know what JavaScript concepts will make your React journey effective and, smoother.

⬖ We will discuss those essential concepts in this thread.

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Swapna Kumar Panda ...
@swapnakpanda
🛣 Beginner's Roadmap for Front-End

HTML & CSS → 👩‍💻 → JavaScript → 👩‍💻
↓
👩‍💻 ← React* ← 👩‍💻 ← Tailwind*
↓
TypeScript → 👩‍💻 → Next.js* → 👩‍💻 → 🏁

⇩

What would we cover?

➊ HTML & CSS
➋ JavaScript
➌ CSS Frameworks
➍ UI Frameworks
➎ TypeScript
➏ Server-side Frameworks
➐ Practice, Practice and, Practice
➑ Other Skills
➒ Frequently Asked Questions

➊ HTML & CSS

⬘ Your Front-End journey shall always start from HTML & CSS and, ends with these as well.

⬗ Don't over burden yourself to learn everything at once. It's a continuous subject.

⬙ Do not separate HTML from CSS. That's


➋ JavaScript

JavaScript is essential. You should start with basics and move to complex subjects.

❍ JavaScript Syntaxes
(preferably ES6 onwards)
❍ HTML DOM API
❍ Event Handling
❍ Fetch


➌ CSS Frameworks

CSS Framework is necessary if you are planning to be a professional developer.

There are so many options available.

❍ Tailwind CSS
❍ Bootstrap
❍ Chakra
❍ Bulma
❍ Foundation
❍ Skeleton
❍ Pure CSS

Start with anything. You can switch any time.
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💎 Direct Link for High-Resolution Image

If you liked this one, give a ⭐️ to this GitHub repo to support my work.

✧ Direct

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Here are those.

➀ all
➁ background
➂ background-position
➃ font
➄ text-align
➅ text-decoration
➆ text-emphasis
➇ list-style
➈ offset
➉ overflow

➀➀ inset
➀➁ inset-block
➀➂ inset-inline
➀➃ margin
➀➄ margin-block
➀➅ margin-inline
➀➆ padding
➀➇ padding-block
➀➈ padding-inline
20. overscroll-behavior
➁➀ scroll-margin
➁➁ scroll-padding

➁➂ border
➁➃ border-top
➁➄ border-right
➁➅ border-bottom
➁➆ border-left
➁➇ border-block
➁➈ border-block-start
30. border-block-end
➂➀ border-inline
➂➁ border-inline-start
➂➂ border-inline-end
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🔗 https://t.co/W1XytKL1MI


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React Hooks are the functions which "hook into" React state and lifecycle features from function components. Hooks allows you to manipulate state and other React feature without writing a class. Let's talk about widely used hook

useEffect hook at a glance 🧵👇🏻


useEffect hook is the heart of React functional components

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Sri Mridanga Saileswari Temple Muzhakkunnu, Kannur KERALA

The temple is established by Parasurama and it is one among 108 Durga temples.
Devi will answer all the prayers of her devotees who pray to her with utmost devotion lighting the ghee deepam.


It is the family diety of Kerala Varma Pazhassi Raja.
Devi is present in three forms Kali, Saraswati and Lakshmi.

Legend...👇
Once a Mridungam ( musical instrument) shaped rock fell from heaven here.
@SriramKannan77


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