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SQL CHEAT SHEET👩‍💻

Here is a quick cheat sheet of some of the most essential SQL commands:

SELECT - Retrieves data from a database

UPDATE - Updates existing data in a database

DELETE - Removes data from a database

INSERT - Adds data to a database

CREATE - Creates an object such as a database or table

ALTER - Modifies an existing object in a database

DROP -Deletes an entire table or database

ORDER BY - Sorts the selected data in an ascending or descending order

WHERE – Condition used to filter a specific set of records from the database

GROUP BY - Groups a set of data by a common parameter

HAVING - Allows the use of aggregate functions within the query

JOIN - Joins two or more tables together to retrieve data

INDEX - Creates an index on a table, to speed up search times.

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SQL Joins ✅

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I’ve never met an awesome software developer who:
- Thought learning new frameworks was a waste.
- Avoided refactoring because “it already works.”
- Avoided debugging because it was frustrating.
- Never deleted code they once proudly wrote.
- Never pushed code that broke in production.
- Stuck to one programming language forever.
- Stopped learning after getting their first job.
- Didn’t rewrite their code later.
- Only worked on projects that felt safe.
- Refused to ask questions when stuck.

Great developers aren’t perfect.

They take risks.
They make mistakes.
They debug endlessly.
They make wrong estimates.

But during all that, They learn.

And that’s exactly why they grow.

Keep that in mind

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Theoretical Questions for Coding Interviews on Basic Data Structures

1. What is a Data Structure?
A data structure is a way of organizing and storing data so that it can be accessed and modified efficiently. Common data structures include arrays, linked lists, stacks, queues, and trees.

2. What is an Array?
An array is a collection of elements, each identified by an index. It has a fixed size and stores elements of the same type in contiguous memory locations.

3. What is a Linked List?
A linked list is a linear data structure where elements (nodes) are stored non-contiguously. Each node contains a value and a reference (or link) to the next node. Unlike arrays, linked lists can grow dynamically.

4. What is a Stack?
A stack is a linear data structure that follows the Last In, First Out (LIFO) principle. The most recently added element is the first one to be removed. Common operations include push (add an element) and pop (remove an element).

5. What is a Queue?
A queue is a linear data structure that follows the First In, First Out (FIFO) principle. The first element added is the first one to be removed. Common operations include enqueue (add an element) and dequeue (remove an element).

6. What is a Binary Tree?
A binary tree is a hierarchical data structure where each node has at most two children, usually referred to as the left and right child. It is used for efficient searching and sorting.

7. What is the difference between an array and a linked list?

Array: Fixed size, elements stored in contiguous memory.

Linked List: Dynamic size, elements stored non-contiguously, each node points to the next.

8. What is the time complexity for accessing an element in an array vs. a linked list?

Array: O(1) for direct access by index.

Linked List: O(n) for access, as you must traverse the list from the start to find an element.

9. What is the time complexity for inserting or deleting an element in an array vs. a linked list?

Array:

Insertion/Deletion at the end: O(1).

Insertion/Deletion at the beginning or middle: O(n) because elements must be shifted.

Linked List:

Insertion/Deletion at the beginning: O(1).

Insertion/Deletion in the middle or end: O(n), as you need to traverse the list.

10. What is a HashMap (or Dictionary)?
A HashMap is a data structure that stores key-value pairs. It allows efficient lookups, insertions, and deletions using a hash function to map keys to values. Average time complexity for these operations is O(1).

Coding interview: https://whatsapp.com/channel/0029VammZijATRSlLxywEC3X

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🔰 How Python Works?

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🧿 Essential React Hooks Part 1

Each hook addresses specific performance, state management, or accessibility needs within React components, allowing for efficient and organized code structure.

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