Oracle: Sum function "not a single-group group function error"

Question

I have an ORDER_LINE table in which I am trying to multiply the NUM_ORDERED of parts by the QUOTED_PRICE for each ORDER_NUM. I am adding SUM() function to group by ORDER_NUM, because if I didn't, there would be multiple entries for the same order.

ORDER_LINE Table:

ORDER_NUM PART_NUM NUM_ORDERED QUOTED_PRICE
21608 AT94 11 21.95
21610 DR93 1 495
21610 DW11 1 399.99
21613 KL62 4 329.95
21614 KT03 2 595
21617 BV06 2 794.95
21617 CD52 4 150
21619 DR93 1 495
21623 KV29 2 1290

Query:

SELECT ORDER_NUM, SUM(NUM_ORDERED * QUOTED_PRICE) AS TOTAL_AMOUNT
FROM
ORDER_LINE
ORDER BY ORDER_NUM;

Expected Result:

ORDER_NUM TOTAL_AMOUNT
21608 241.45
21610 894.99
21613 1319.8
21614 1190
21617 2189.9
21619 495
21623 2580

Error ORA-00937: not a single-group group function

If I remove the Sum function I get the following result:

SELECT ORDER_NUM, (NUM_ORDERED * QUOTED_PRICE) AS TOTAL_AMOUNT
FROM
ORDER_LINE
ORDER BY ORDER_NUM;
ORDER_NUM TOTAL_AMOUNT
21608 241.45
21610 495
21610 399.99
21613 1319.8
21614 1190
21617 1589.9
21617 600
21619 495
21623 2580

Answer 1

Unless I'm missing something, you just need to add GROUP BY ORDER_NUM, don't you?

SELECT ORDER_NUM, SUM(NUM_ORDERED * QUOTED_PRICE) AS TOTAL_AMOUNT
FROM
ORDER_LINE
GROUP BY ORDER_NUM
ORDER BY ORDER_NUM;