Question

I have 2 tables

Bid_customer

|bidkey | customerkey
|  1    | 1
|  1    | 2
|  1    | 3

customer_groups

| groupkey | customerkey 
|    1     |      1
|    1     |      2
|    1     |      3

What I’m trying to get is a result that will look like

| bidkey | groupkey
|    1   |      1

I’ve tried a cursor and joins but just don’t seem to be able to get what i need any ideas or suggestions

EDIT: customers can belong to more that one group also

Answer 1

In order to have a working Many-to-Many relationship in a database you need to have an intermediary table that defines the relationship so you do not get duplicates or mismatched values.

This select statement will join all bids with all groups because the customer matches.

Select bidkey, groupkey
From customer_groups
Inner Join bid_customer
Where customer_groups.customerkey = Bid_customer.customerkey

Hers is a sample Many to Many Relationship:

For your question:
You will need another table that joins the data. For example, GroupBids

customer_groups and bid_customer would have a one-to-many relationship with GroupBids

You would then do the following select to get your data.

Select bidkey, groupkey 
From bid_customer 
inner join GroupBids 
   ON bid_customer.primarykey = GroupBids.idBidKey
inner join customer_groups 
   ON customer_groups.primarykey = GroupBids.idCustomerGroupkey

This would make sure only related groups and bids are returned