GROUP BY: one summary per group
GROUP BY combines rows with equal grouping values. Each group gets its own aggregate. Include grouped columns or aggregate expressions in your SELECT for portable, predictable SQL.
हिन्दी में समझें
GROUP BY समान मानों की पंक्तियाँ मिलाता है। हर समूह का सार अलग निकलता है। SELECT में समूह के कॉलम या एग्रीगेट ही रखें।
अभ्यास: department और AVG(salary) को avg_salary: विभाग अनुसार समूह और क्रम।
Hinglish mein samjhein
GROUP BY same values ki rows group karta hai. Har group ka aggregate alag milta hai. SELECT mein grouped columns ya aggregates rakho.
Practice: department aur AVG(salary) AS avg_salary, department se group aur sort karo.
A small SQL example
SELECT category, COUNT(*) AS total FROM products GROUP BY category ORDER BY category;Examples use the fictional shop database bundled with the SQL playground: customers, products, orders, order_items and employees. The engine is SQLite; other SQL dialects may differ.
Try this example in the SQL playground →Practise this idea
Show department and AVG(salary) as avg_salary, grouped and ordered by department.
Check answer & explanation
SELECT department, AVG(salary) AS avg_salary FROM employees GROUP BY department ORDER BY department;GROUP BY department creates one group per department. AVG(salary) calculates an independent average for each group.
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Check your understanding
GROUP BY creates…
Check the quiz answer
One summary per group
GROUP BY combines rows with equal grouping values. Each group gets its own aggregate. Include grouped columns or aggregate expressions in your SELECT for portable, predictable SQL.
References & corrections
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