/* Accumulate total amount from all previous rows using implicit frame */

SELECT payment_num, vendor, description, pay_date, amount, 
       SUM(amount) OVER (ORDER BY payment_num) AS accum_total 
FROM   payment;


/* Same, but using an explicit frame */

SELECT payment_num, vendor, description, pay_date, amount, 
       SUM(amount) OVER (ORDER BY payment_num ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS accum_total 
FROM   payment;


/* Accumulate total amount by vendor */

SELECT payment_num, vendor, description, pay_date, amount, 
       SUM(amount) OVER (PARTITION BY vendor ORDER BY payment_num) AS accum_total 
FROM   payment;


/* A rolling/sliding 2 rows average */

SELECT payment_num, vendor, description, pay_date, amount, 
       AVG(amount) OVER (ORDER BY payment_num ROWS BETWEEN 1 PRECEDING and CURRENT ROW) AS accum_total 
FROM   payment;



/* Running total of student_id using implicit frame */

SELECT student_id, SUM(student_id) OVER (ORDER BY student_id) AS accum 
FROM   student;