📊 Top 5 Data Analyst Interview Q&A You Should Know 🚀

1️⃣ What is the difference between SQL JOIN and UNION?

✅ JOIN combines columns from multiple tables based on a related key.

✅ UNION combines rows from multiple queries into a single result set.

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2️⃣ What is the difference between a Measure and a Calculated Column in Power BI?

✅ Calculated Column → Computed row by row and stored in the model.

✅ Measure → Calculated dynamically based on filters and visuals.

⚡ Measures are more memory efficient and commonly used in dashboards.

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3️⃣ What is the purpose of GROUP BY in SQL?

✅ GROUP BY is used to aggregate data based on one or more columns.

📌 Commonly used with:
• COUNT()
• SUM()
• AVG()
• MAX()
• MIN()

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4️⃣ What is ETL in Data Analytics?

✅ ETL = Extract, Transform, Load

📥 Extract → Collect data from sources
🔄 Transform → Clean & process data
📤 Load → Store data into database/warehouse

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5️⃣ What is the difference between WHERE and HAVING in SQL?

✅ WHERE filters rows before aggregation.

✅ HAVING filters grouped/aggregated data after aggregation.

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