How to access child records from an inner query in apex [duplicate]

Question

This question already has an answer here:

• Dynamic SOQL, Access Subquery Results 1 answer

I have a piece of code in my Apex:

List<sObject> assessmentToQuestions = [
            SELECT Id, (SELECT Id FROM zced__Assessment_Questions__r) questions
            FROM zced__Assessment__c
            WHERE zced__Interaction__c = :interactionId
        ];

        Set<String> questionsIds = new Set<String>();
        for(sObject assessment: assessmentToQuestions) {
            for(sObject question: assessment.questions) {
                questionsIds.add(question);
            }
        }

The code above does not work because it does not allow me to use alias for the list of Id over here:

(SELECT Id FROM zced__Assessment_Questions__r) questions

I saw the application of an alias over here and tried to do the same, but got an error. So, my question here is how can I use an alias in the case?

Oh (this question in case if it is an x-y problem) how can I approach the problem of iterating the list in another way? I need to be able to iterate over all the Id extracted over here:

(SELECT Id FROM zced__Assessment_Questions__r)

Answer 1

Alias does not work with parent-to-child queries; however, you can access the query result set of zced__Assessment_Questions__r as follows:

for (zced__Assessment__c zced__Assessment : [
        SELECT Id, (SELECT Id FROM zced__Assessment_Questions__r)
        FROM zced__Assessment__c
        WHERE zced__Interaction__c = :interactionId
]) {
    zced__Assessment.zced__Assessment_Questions__r;
}