Why 2 similar codes - 1 works the other doesnt?

Question

1st Code:
INSERT INTO DWCUSTOMERTEST
(CUSTOMER_KEY,CITY,STATE,POSTAL_CODE,GENDER,REGION,COUNTRY,OCCUPATION)
SELECT CUSTOMER_KEY.NEXTVAL AS customer_key, CITY, STATE, POSTAL_CODE, GENDER, 'N' AS REGION,
'Australia' AS COUNTRY, OCCUPATION FROM NAUSCUSTOMER
WHERE rowid NOT IN (SELECT row_id FROM ERROR_EVENT WHERE table_name='NAUSCUSTOMER');
THIS CODE INSERTS THE ROW PERFECTLY INTO DWCUSTOMERTEST
2nd Code:
INSERT INTO DWPURCHASESTEST
(PRODUCT_ID,TIME_KEY,C.CUSTOMER_KEY,SHIP_DATE,COST_PRICE,SELL_PRICE,
PURCHASE_PRICE,SHIPPING_CHARGE)
SELECT P.PRODUCT_ID, TIME_KEY, CUSTOMER_KEY, SHIP_DATE, P.COST_PRICE, P.SELL_PRICE, N.PURCHASE_PRICE, N.SHIPPING_CHARGE
FROM PRODUCT P, TIME, DWCUSTOMERTEST C,NAUSPURCHASES N
WHERE rowid NOT IN (SELECT row_id FROM ERROR_EVENT WHERE table_name='NAUSPURCHASES');
THIS DOES NOT INSERT INTO DWPURCHASESTEST. It gives the following error:
WHERE rowid NOT IN (SELECT row_id FROM ERROR_EVENT WHERE table_name='NAUSPURCHASES')
ERROR at line 8:
ORA-00918: column ambiguously defined
I understand the meaning of the error. But I don't understand what is wrong. Can someone please shine a light?

Answer 1

I have entered this code in:
INSERT INTO DWPURCHASESTEST
(PRODUCT_ID,TIME_KEY,CUSTOMER_KEY,SHIP_DATE,COST_PRICE,SELL_PRICE,
PURCHASE_PRICE,SHIPPING_CHARGE)
SELECT N.PRODUCT_ID, N.TIME_KEY , C.CUSTOMER_KEY , N.SHIP_DATE, P.COST_PRICE, P.SELL_PRICE, N.PURCHASE_PRICE, N.SHIPPING_CHARGE
FROM PRODUCT P ,NAUSPURCHASES N, DWCUSTOMER C
WHERE C.rowid NOT IN (SELECT row_id FROM ERROR_EVENT WHERE table_name='NAUSPURCHASES')
BUT i get 0 rows created. I don't understand why. In order for you to understand the situation better:
DWCUSTOMERTEST(CUSTOMER_KEY, CITY, STATE, POSTAL_CODE, GENDER, REGION,
COUNTRY, OCCUPATION)
DWPURCHASESTEST(PRODUCT_ID, TIME_KEY, CUSTOMER_KEY, SHIP_DATE, COST_PRICE,
SELL_PRICE, PURCHASE_PRICE, SHIPPING_CHARGE)
THESE are the 2 table schemas
CUSTOMER_KEY is a surrogate key. Several filters have been made and recorded to the ERROR_EVENT TABLE prior to this attempt at populating DWPURCHASESTEST.
Does anyone know how to solve my problem? If it aint clear, what other information do you guys need? Thanks so much