BigQuery 联接表

Question

Example, I have 2 tables.

Pet

PetID	PetName	PetType
123	Charlie	Dog
456	Rose	Cat
789	Sam	Rabbit

Owner

PetID	OwnerName	OwnerNumber
123	Phil	1234567
123	Carly	2345678
456	Russel	3456789
456	Sophie	4567891
789	Tasha	5678912
890	Bill	6789012
901	Shay	7890123

I want the result to be:

PetID	OwnerName	OwnerNumber	PetName
123	Phil	1234567	Charlie
456	Russel	3456789	Rose
789	Tasha	5678912	Sam

I only want the PetId's that are in Pet. I only want distinct PetId's. How would I go about this in BigQuery? Inner Join?

Thank you

Answer 1

I would rather go with

select o.*, PetName
from owner o
join pet p
using (PetID)
where true 
qualify row_number() over(partition by PetID) = 1    

If applied to sample data in your question - output is

Answer 2

This looks like a simple join but you have to restrict to a single pet id. You can use qualify :

select p.*, o.ownernumber
from pet p join
     owner o
     using (petid)
where 1=1
qualify row_number() over (partition by petid order by petid) = 1;

You can use the order by to control which owner you get.