Window Functions
GROUP BY, ki, TARAH, window, functions, aggregation, karte, hain, LEKIN, HAR, individual, row, KO, RESULT, mein, RAKHТE, hain, EK, EXTRA, computed, column, ke, saath — ROW_NUMBER(), RANK(), aur, aggregate, functions, (SUM, AVG) sab, "OVER" clause, ke, saath, use, ho, sakte, hain.
PARTITION BY, (window, function, ke, ANDAR) rows, ko, GROUPS, mein, DIVIDE, karta hai — HAR, PARTITION, ke, liye, ALAG, se, calculation, hoti, hai (GROUP BY, jaisa, LEKIN, rows, collapse, NAHI, hote).
SELECT
name, department, salary,
RANK() OVER (PARTITION BY department ORDER BY salary DESC) AS dept_rank
FROM employees;
-- Har department, ke, andar, salary, ke, hisaab, se, rank- Window functions = row-level, aggregation, — rows, collapse, nahi, hote
- ROW_NUMBER(), RANK(), aggregate, functions, "OVER" clause, ke, saath
- PARTITION BY, = rows, ko, groups, mein, divide, karta, hai, calculation, ke, liye
LAG(), PREVIOUS, row, ki, VALUE, deta hai (CURRENT, ROW, ke, RELATIVE). LEAD(), NEXT, row, ki, VALUE, deta hai — jaise, EK, MONTH-OVER-MONTH, growth, calculate, karne, ke, liye.
SELECT month, revenue,
LAG(revenue) OVER (ORDER BY month) AS prev_month_revenue
FROM monthly_sales;SUM() OVER (ORDER BY date), EK, RUNNING, TOTAL, (CUMULATIVE, SUM) calculate, karta hai — HAR, row, tak, ka, TOTAL, dikhata, hai, jaise, EK, BANK, statement, ka, running, balance.