Sub-query Join Error

Question

"Using subquery, list all product (product number, brand, and category) whose overall number of orders (containing that product) is greater than 500"

Before sub-query I tried using a join:

SELECT PRODUCT.PRODUCT_NO, PRODUCT.BRAND,PRODUCT.PRODUCT_CATEGORY
FROM PRODUCT JOIN ORDERLINE
ON PRODUCT.PRODUCT_NO = ORDERLINE.PRODUCT_NO
WHERE SUM(ORDERLINE_NO) >= 500 ;

And got the following error;

 ORA-00934: group function is not allowed here 00934. 00000 - "group function is not allowed here" *Cause: *Action: Error at Line: 28 Column: 6 

Answer 1

You are almost there but since you've used aggregate function, you must have a GROUP BY clause and a HAVING clause to filter the aggregated result:

SELECT PRODUCT.PRODUCT_NO, 
       PRODUCT.BRAND,
       PRODUCT.PRODUCT_CATEGORY 
FROM PRODUCT JOIN ORDERLINE ON PRODUCT.PRODUCT_NO = ORDERLINE.PRODUCT_NO 
GROUP BY PRODUCT.PRODUCT_NO, 
       PRODUCT.BRAND,
       PRODUCT.PRODUCT_CATEGORY
HAVING COUNT(ORDERLINE_NO) >= 500 ;

And use COUNT() instead of SUM() .

Answer 2

Try this:

not sure if this is what you want

SELECT PRODUCT.PRODUCT_NO, PRODUCT.BRAND,PRODUCT.PRODUCT_CATEGORY
FROM PRODUCT JOIN ORDERLINE
ON PRODUCT.PRODUCT_NO = ORDERLINE.PRODUCT_NO
GROUP BY PRODUCT.PRODUCT_NO, PRODUCT.BRAND,PRODUCT.PRODUCT_CATEGORY
HAVING COUNT(ORDERLINE_NO) >= 500 ;