SQL Cheatsheet
SELECTโ
SELECT col1, col2 FROM table WHERE condition ORDER BY col1 LIMIT 10;
JOINโ
SELECT * FROM a JOIN b ON a.id = b.a_id;
SELECT * FROM a LEFT JOIN b ON a.id = b.a_id;
GROUP BYโ
SELECT category, COUNT(*) FROM products GROUP BY category;
SELECT category, AVG(price) FROM products GROUP BY category HAVING AVG(price) > 100;
INSERT / UPDATE / DELETEโ
INSERT INTO table (col1, col2) VALUES (val1, val2);
UPDATE table SET col1 = val1 WHERE condition;
DELETE FROM table WHERE condition;
INDEXโ
CREATE INDEX idx_name ON table (col);
CREATE UNIQUE INDEX idx_unique ON table (col);
Transactionโ
BEGIN;
UPDATE accounts SET balance = balance - 100 WHERE id = 1;
UPDATE accounts SET balance = balance + 100 WHERE id = 2;
COMMIT;