Child to Parent Relationship

What Is SOQL Relationship Queries?

Relationship queries involve at least two objects, a parent and a child. These queries are used to fetch data either from the Parent object when the SOQL query is written on the child, or from the child object when the SOQL query is written on the parent.

What Is Child To Parent Query In Salesforce?

Whenever we need to fetch data from parent object fields with child records, then the query we use is child-to-parent.

For Standard Objects

 SELECT Field_Name.Parent_Obj_Field FROM Child_Object;
List < Opportunity > oppList = [SELECT Name, Amount, CloseDate, Account.Name
    FROM Opportunity
];
for (Opportunity o: oppList) {
    System.debug('Opp: ' + o.Name + ' Acc: ' + o.Account.Name);
}

For Custom Objects

SELECT(Field_Name) __r.Parent_Obj_Field FROM child_object;
List < Branch__c > branchList = [SELECT Branch_ID__c, State__c,
    Branch_of_Bank__r.Bank_Name__c from Branch__c
];
for (Branch__c bl: branchList) {
    System.debug('Bank Name: ' + bl.Branch_of_Bank__r.Bank_Name__c + 'Branch: ' + bl.State__c);
}