Cross Object SOQL Query

Question

I have three objects

Object A - Parent Object B - Child ( Lookup to A) Object C - Child (Lookup to A)

B and C are not related directly, I have to fetch the fields from object C where my query is written on Object B.

Now, I have already a query written on Object B through which I am fetching some fields from Object A but not sure how can I modify it to fetch the fields from Object C or I have to write a separate query altogether to fetch the fields from C.

Answer 1

Relationships between the object are as below

• ObjectB - No Parent
• ObjectA - Parent ObjectB
• ObjectC - Parent OjbectA

As per salesforce soql limitations.

In each specified relationship, only one level of parent-to-child relationship can be specified in a query.

Hence you have to use two different queries to get ObjectC records, if you want to keep existing query on objectB. Total 2 queries will be required to get data from all 3 objects.

Workaround for single query:

While taversing from child to parent you can go 5 levels up. By using middle object ObjectA you can get all 3 object fields.

E.g

SELECT 
    Id, Name, ..........,
    ObjectB.Id,  ObjectB.Name ........,
    (
        SELECT
            Id, Name,.....
            FROM
            ObjectC__r
    )
FROM ObjectA