Latest Questions 214 total
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166What is the difference between AWS S3 and EBS?
**Amazon S3 (Simple Storage Service):**
- Object storage — stores files, images, backups, static websites
- Accessible from anywhere over ...
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167How to build a RAG chatbot with LangChain and Python?
Here is a simple RAG chatbot using LangChain:
```python
from langchain_openai import ChatOpenAI, OpenAIEmbeddings
from langchain_community....
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168What are the core AWS services every developer should know?
Essential AWS services for developers:
**Compute:**
- EC2 — virtual servers
- Lambda — serverless functions
- ECS/EKS — container orc...
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169What is the difference between ChatGPT, Claude, and Gemini?
All three are large language model (LLM) AI assistants:
| | ChatGPT | Claude | Gemini |
|---|---|---|---|
| Company | OpenAI | Anthropic | ...
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170What is prompt engineering and why does it matter?
Prompt engineering is the practice of designing and optimising text inputs (prompts) to get better outputs from AI language models.
**Why i...
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171How to prepare for a data science interview in 30 days?
**Week 1 — Statistics & Probability**
- Probability distributions, Bayes theorem
- Hypothesis testing, p-values
- A/B testing basics
**We...
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172Most common system design interview questions for software engineers
Top system design questions asked at product companies:
1. **Design a URL shortener** (Bit.ly)
2. **Design Twitter/Instagram** (social medi...
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173What is the difference between useState and useEffect in React?
**useState** — manages state (data that can change over time)
**useEffect** — handles side effects (API calls, subscriptions, timers)
`...
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174What is async/await in JavaScript?
**async/await** is syntactic sugar over Promises that makes asynchronous code look synchronous.
```javascript
// With Promises
fetch('/api/...
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175What is the difference between var, let, and const in JavaScript?
All three declare variables, but with different scope and mutability:
**var:** function-scoped, hoisted, can be redeclared
**let:** block-s...
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176How do you find duplicate rows in SQL?
```sql
-- Find duplicates by email
SELECT email, COUNT(*) as count
FROM users
GROUP BY email
HAVING COUNT(*) > 1;
-- Delete duplicates, kee...
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177What is the difference between WHERE and HAVING in SQL?
**WHERE** filters rows BEFORE grouping
**HAVING** filters groups AFTER GROUP BY
```sql
-- WHERE: filter individual rows
SELECT * FROM emplo...
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178What is the difference between INNER JOIN and LEFT JOIN in SQL?
**INNER JOIN** — returns only rows where there is a match in BOTH tables
**LEFT JOIN** — returns ALL rows from the left table + matching...
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179Top 10 Python interview questions for data science jobs
Here are the most commonly asked Python questions in data science interviews:
1. Difference between list, tuple, and set
2. Explain generat...
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180Is Python enough to get a data science job?
Python alone is NOT enough, but it's the most important skill.
You need:
1. **Python** (Pandas, NumPy, Scikit-learn, Matplotlib)
2. **SQL**...
