Latest Questions 84 total
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46How 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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47What 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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48What 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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49Top 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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50Is 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**...
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51How many months does it take to learn full stack development?
Timeline to become job-ready in full stack:
**With dedicated learning (6-8 hours/day):**
- HTML/CSS/JS basics: 1 month
- React (frontend): ...
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52What is the average salary for a data science fresher in India 2025?
For freshers in India (2025 data):
- **Entry level (0-1 year):** ₹3.5 – ₹7 LPA
- **Junior Data Scientist (1-3 years):** ₹6 – ₹1...
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53How to get a data science job with no experience?
Getting your first data science job without experience is challenging but very doable. Here's a proven roadmap:
1. **Build skills** — Pyt...
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54What is Docker and why do developers use it?
Docker is a containerisation platform that packages your application and all its dependencies into a portable container.
**Why use it:**
- ...
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55What is the difference between AWS EC2 and Lambda?
**EC2 (Elastic Compute Cloud):** Virtual servers you manage
- You control OS, software, scaling
- Always running → pay for uptime
- Best f...
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56What is Node.js and why is it used?
Node.js is a JavaScript runtime built on Chrome's V8 engine that lets you run JavaScript on the server side.
**Why use it:**
- **Non-blocki...
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57What is the difference between SQL and NoSQL databases?
**SQL (Relational):** MySQL, PostgreSQL, SQLite
- Structured tables with fixed schema
- ACID compliant (reliable transactions)
- Best for co...
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58What is REST API and how does it work?
REST (Representational State Transfer) is an architectural style for building APIs.
Key principles:
- **Stateless** — each request is ind...
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59What is the difference between React and Angular?
| Feature | React | Angular |
|---|---|---|
| Type | Library | Full framework |
| Language | JavaScript | TypeScript |
| Learning curve | Mo...
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60What is the difference between correlation and causation?
**Correlation** — two variables change together (positive or negative relationship)
**Causation** — one variable directly causes the cha...
