Help with SOQL Query

Question

I have a custom object Contract__c, which is in a relationship with Address__c. A Contract can have many Addresses, so Adress__c has a lookup field to Contract__c.

I am trying to query all the Addresses related to a contract, but I seem to be having difficulties:

SELECT Id, (SELECT Id FROM Address__c) FROM Contract__c

What am I doing wrong here?

Answer 1

You need to go by the relationship which is likely:

SELECT Id, (SELECT Id FROM Address__r) FROM Contract__c

In order to find the correct relationship name you can look here: How to find out relationships for SOQL queries?

EDIT: Expand your project and its on the bottom of Eclipse.

Answer 2

In Relationship Queries For parent-to-child relationships, the parent object has a name for the child relationship that is unique to the parent, the plural of the child object name.

In your case, the query should be:

SELECT Id, (SELECT Id FROM Addresses__r) FROM Contract__c

Let me know whether it works.

Answer 3

Address__r is the relationship name of the Address__c to Contract__c

newAddress is holding all the value of Address__c from trigger.new, So if you have a list of Address then you can use that List of Address instead of newAddress this query will return the Contract related to all Addresses

List<Contract__c> conList = [Select Id,(Select Id from Address__r) from Contract__c where Id IN (Select Address__c from Address__c where Id IN :newAddress)];

If you want to query for single address then simply write the condition for the address in where Clause like:

List<Contract__c> conList = [Select Id,(Select Id from Address__r) from Contract__c where Id IN (Select Address__c from Address__c where Id = '0092813000vzvu1')];