oracle sql - merge table with nested table as column - sql

Question

I have 2 tables and one nested table:
1.stores data about products which include following columns:
ITEM - product id(key)
STORE - store id(key)
PRICE
NORMAL_PRICE
DISCOUNTS - nested table with info about discounts include columns:
PromotionId(key)
PromotionDescription
PromotionEndDate
MinQty
DiscountedPrice
DiscountedPricePerMida
2- temp table with new discounts include columns:
PROMOTIONID(key)
PRODUCTID(key)
PROMOTIONDESCRIPTION
PROMOTIONENDDATE
MINQTY
DISCOUNTEDPRICE
DISCOUNTEDPRICEPERMIDA
What i need to do is merge table 2 into table 1 - if no match insert else ignore
(when match is: product id matching in table 1 and 2 and for this product sub table PROMOTIONID match PROMOTIONID from table 2)
This is where I got so far and I have difficulty with nested part - ON clause and Insert clause
MERGE INTO PRICES P
USING(SELECT * FROM TMP_PROMO)T
ON(P.ITEM=T.PRODUCTID AND P.STORE=50 AND P.DISCOUNTS.PROMOTIONID=T.PROMOTIONID)
WHEN NOT MATCHED THEN INSERT (P.DISCOUNTS)
VALUES(T.PROMOTIONID,
T.PROMOTIONDESCRIPTION,
T.PROMOTIONENDDATE,
T.MINQTY,
T.DISCOUNTEDPRICE,
T.DISCOUNTEDPRICEPERMIDA);
I know that this is wrong but I can't find anywhere how to do it
example:
Prices table:
row1(1,50,...,nested_table[(11,...),(12,...)])
row2(2,50,...,nested_table[(10,...),(12,...)])
new promo table:
(15,1,...)
(11,1,...)
new promo with id 15 will be added to row1 and row2
and promo with id 11 will not be added
Please help,
thanks

Answer 1

What you intend to do is not realy a MERGE. You are adding a new promotion in each record that doesn't contain it.
Below is an answer how yu would approach it if you would use not a nested table but a conventional child table.
Setup (simplified to a minimum)
create table ITEM
(ITEM_ID NUMBER PRIMARY KEY);
create table ITEM_PROMO
(ITEM_ID NUMBER REFERENCES ITEM(ITEM_ID),
PROMO_ID NUMBER);
create table TMP_PROMO
(PROMO_ID NUMBER);
insert into ITEM values (1);
insert into ITEM values (2);
insert into ITEM_PROMO values (1,11);
insert into ITEM_PROMO values (1,12);
insert into ITEM_PROMO values (2,10);
insert into ITEM_PROMO values (2,12);
insert into TMP_PROMO values (15);
insert into TMP_PROMO values (11);
commit;
The first thing you need to find is which promotions are missing for an item.
Use a cross join to get all combination and constrain those promotions that EXISTS for a particular ITEM_ID:
select ITEM.ITEM_ID, TMP_PROMO.PROMO_ID
from ITEM cross join TMP_PROMO
where NOT EXISTS (select NULL from ITEM_PROMO where ITEM_ID = ITEM.ITEM_ID and PROMO_ID = TMP_PROMO.PROMO_ID)
;
This gives as expected
ITEM_ID PROMO_ID
---------- ----------
2 11
1 15
2 15
Now simple add those new promotions
INSERT INTO ITEM_PROMO
select ITEM.ITEM_ID, TMP_PROMO.PROMO_ID
from ITEM cross join TMP_PROMO
where NOT EXISTS (select NULL from ITEM_PROMO where ITEM_ID = ITEM.ITEM_ID and PROMO_ID = TMP_PROMO.PROMO_ID)
;
This should give you a hint how to approach while using nested tables (or how to change the DB design:)