Joins & Relationships
INNER JOIN
Matching Rows Only
💡 INNER JOIN, EK, "VENN, DIAGRAM, ka, OVERLAP" hai — SIRF, WOHI, rows, RETURN, hote, HAIN, JO, DONO, tables, mein, MATCH, karti, HAIN, jaise, DO, LISTS, ki, COMMON, ITEMS.
INNER JOIN, DO, tables, ko, COMBINE, karta hai, EK, MATCHING, condition, ke, BASIS, PAR — SIRF, WOHI, rows, RESULT, mein, AATI, HAIN, JAHA, DONO, tables, mein, MATCH, MILТА, hai.
Multiple, JOINS, CHAIN, kiye, ja, sakte, hain, MULTIPLE, tables, ko, EK, saath, COMBINE, karne, ke, liye (jaise, users, orders, aur, products).
SELECT users.name, orders.amount
FROM users
INNER JOIN orders ON users.id = orders.user_id;
-- 3-table join:
SELECT users.name, orders.id, products.name AS product_name
FROM users
INNER JOIN orders ON users.id = orders.user_id
INNER JOIN order_items ON orders.id = order_items.order_id
INNER JOIN products ON order_items.product_id = products.id;🔗
INNER JOIN, EK, "VENN, DIAGRAM, ka, OVERLAP" hai — SIRF, WOHI, rows, RETURN, hote, HAIN, JO, DONO, tables, mein, MATCH, karti, HAIN, jaise, DO, LISTS, ki, COMMON, ITEMS.
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⚡ झट से Recap
- INNER JOIN = sirf, matching, rows, RETURN, karta, hai, DONO, tables, se
- ON clause = join, condition, specify, karta, hai
- Multiple, joins, chain, kiye, ja, sakte, hain, multiple, tables, ke, liye
इस page में (2 subtopics)
Purana, "implicit" join, syntax, (FROM a, b WHERE a.id = b.a_id) still, kaam, karta, hai, LEKIN, MODERN, explicit, JOIN, syntax, (FROM a INNER JOIN b ON ...) STRONGLY, PREFERRED, hai — readability, aur, JOIN, type, ko, CLEAR, karta hai.
-- Modern, PREFERRED, syntax:
SELECT * FROM a INNER JOIN b ON a.id = b.a_id;ON, clause, mein, AND, se, MULTIPLE, conditions, combine, ki, ja, sakti, hain — jaise, EK, join, jo, DATE, RANGE, aur, ID, MATCH, DONO, PAR, DEPEND, karta hai.
Tip: Multiple-condition, joins, aksar, temporal, data, (jaise, "kaun, sa, price, tha, USE, DATE, PAR") ke, liye, use, hote, HAIN.