INNER JOIN: connect the dots
An INNER JOIN returns matching row pairs. Connect tables through related keys using ON. Use short table aliases and qualify ambiguous columns. One-to-many joins may create multiple rows per customer.
हिन्दी में समझें
INNER JOIN मिलती पंक्तियों की जोड़ियाँ देता है। ON से संबंधित कुंजियाँ जोड़ें। छोटे नाम और कॉलम का टेबल नाम रखें। एक ग्राहक की कई पंक्तियाँ आ सकती हैं।
अभ्यास: केवल paid orders का order id और ग्राहक name, order id क्रम में।
Hinglish mein samjhein
INNER JOIN matching row pairs deta hai. ON se related keys connect karo. Aliases aur qualified columns use karo. One-to-many join se multiple rows aa sakti hain.
Practice: Paid orders ke order id aur customer name, order id sorted.
A small SQL example
SELECT o.id, c.name FROM orders AS o JOIN customers AS c ON o.customer_id = c.id ORDER BY o.id;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 order id and customer name for paid orders only, ordered by order id.
Check answer & explanation
SELECT o.id, c.name FROM orders o JOIN customers c ON o.customer_id=c.id WHERE o.status='paid' ORDER BY o.id;ON relates each order to its customer. WHERE then keeps paid orders, and ORDER BY o.id makes the output deterministic.
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Check your understanding
The join condition usually belongs after…
Check the quiz answer
ON
An INNER JOIN returns matching row pairs. Connect tables through related keys using ON. Use short table aliases and qualify ambiguous columns. One-to-many joins may create multiple rows per customer.
References & corrections
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