Question

I have got Two Tables

Product (Id, Name, CCode)

Category (CCode, CatName) – No Primary Key

Insert Into ProductNew (DW_Prod_Id, ProdId, ProdName, CC, CName)

Select Dw_Prod_Id.Nextval, Id, Name, CCode,

    (Select CatName
     From Category cc, Product p
     Where  cc.CCode IN p.CatCode
     Group By CatName ) 

From Product;

SQL Error: ORA-01427: single-row subquery returns more than one row
01427. 00000 – “single-row subquery returns more than one row”

I am getting the above error Because my SubQuery returns more than one row.
I would like to Match the CatCode of each row from Product table to the Category Table so that I can obtain the CatName and then Insert rows into my New Table 🙂

Answer 1

if product can have only one category :

INSERT INTO ProdcutNew (DW_Prod_Id, ProdId, ProdName, CC, CName)

(SELECT Dw_Prod_Id.Nextval, p.Id, p.Name, cc.CCode, cc.CName
FROM Product p
INNER JOIN Category cc on p.CatCode = cc.CCode)

And you can correct your table name

ProdcutNew

to ProductNew 😉

EDIT :

But if, as @Gordon Linoff pointed, you have duplicates CCode, this won’t work.

If you don’t want a primary key on Category table, add at least a unique constraint (you’ll have to clean your datas first)

ALTER TABLE Category ADD CONSTRAINT Unique_code UNIQUE(CCode);

EDIT 2 :

But the proper way would be :

Add an Id in Category as PK, and use it as Category_ID FK in Product (if CCode can change)
With the unique constraint on CCode.