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ADG SOQL subquery working for standard objects and not for custom objects
I have a SOQL query which works fine:
But the following queries, which have been similarly formed as the above, do not run:
where Review__c is child object of Job_Application__c
So I have 2 questions:
1. Is it a limitation that such queries (with sub-queries to child object) work only for standard objects and not for custom objects?
2. In the first query, why does the sub-query uses the object name "Contacts" and not "Contact" which is the actual object name?
SELECT Id, Name, (SELECT Id,Name FROM Contacts)
FROM Account
WHERE Name = 'Apollo'
But the following queries, which have been similarly formed as the above, do not run:
SELECT Id, Candidate_Name__c, (SELECT Id,Assessment__c FROM Review__c)
FROM Job_Application__c
WHERE Candidate_Name__c = 'Jamie Sandras'
Error: "Didn't understand relationship 'Review__c' in FROM part of query call...."
SELECT Id, Candidate_Name__c, (SELECT Id,Assessment__c FROM Review__r)
FROM Job_Application__c
WHERE Candidate_Name__c = 'Jamie Sandras'
Error: "Didn't understand relationship 'Review__r' in FROM part of query call...."where Review__c is child object of Job_Application__c
So I have 2 questions:
1. Is it a limitation that such queries (with sub-queries to child object) work only for standard objects and not for custom objects?
2. In the first query, why does the sub-query uses the object name "Contacts" and not "Contact" which is the actual object name?
SELECT Id, Name, (SELECT Id,Name FROM Contacts) FROM Account ....
Please follow below step :-
1) Click on Review object
2) Then search Job_Application lookup
Your query should like below
All Answers
Understanding Foreign Key and Parent-Child Relationship SOQL Queries
1) https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/langCon_apex_SOQL_foreign_key.htm
Basic SOQL Relationship Queries
2) https://developer.salesforce.com/blogs/developer-relations/2013/05/basic-soql-relationship-queries.html
A Deeper look at SOQL and Relationship Queries on Force.com
3) https://developer.salesforce.com/page/A_Deeper_look_at_SOQL_and_Relationship_Queries_on_Force.com
Using Relationship Queries
4) https://developer.salesforce.com/docs/atlas.en-us.soql_sosl.meta/soql_sosl/sforce_api_calls_soql_relationships_query_using.htm
Lets Elaborate the Example Using Account and Contact.
--> Parent Object : Account
--> Child Object : Contact
--> Child Relationship Name : This is very important and is required for parent to child queries. You can find the same in the relationship field that relates the child object to account. In our case it is "Account" which is located @Contact. So if you go to detail of this field you will find the Child Relationship Name, which should be "Contacts". So the child to parent relationship will have this in its from statement. If it was a custom object you will have to add "__r"
NOTE:- Please click on lookup field and then check your child relationship name
Try the below one,
As per your query,
Parent Object : Job_Application__c
Child Object: Review__c
Step 1: Go to child object review.
Step 2: Find the relationship field(lookup/master) to the job application object.
Step 3: Click on the relationship field.
Step 4: On the detail of relationship field you will find the "Child Relationship Name".
Step 5: Copy the Child relationship name.
Step 6: Build query as follow,
SELECT Id, Candidate_Name__c, (SELECT Id,Assessment__c FROM Review__r) FROM Job_Application__c WHERE Candidate_Name__c = 'Jamie Sandras'
Please follow below step :-
1) Click on Review object
2) Then search Job_Application lookup
Your query should like below
I am now able to work it out fine.
child object student
Here,i am doing count all the student who are associated with particular school object.
I am using subquery which is working perfectly,If you find this suitable Plz like the Content
Code:
void validateCount(list<student__c> TN)
{
list<school__c> lstSch=new list<school__c>();
set<id> idset=new set<id>();
for(student__c objST:TN)
{
if(objSt.School__c!=null)
{
idSet.add(objST.School__c);
}
}
if(idSet.size()>0)
{
for(school__c objSch:[select id,number_of_student__c,(select id from Students__r) from school__c where id in:idset])
{
objSch.number_of_student__c=ObjSch.Students__r.size();
lstSch.add(objSch);
}
if(lstSch.size()>0)
{
update lstSch;
}
}
}