Go to setup, click on the search bar and type objects or go to setup, then go to Create than select objects

than create the required objects. Here is one example of creating a custom object:

Than click on new button you’ll able to see the page shown below.

After creating all the required objects you do need to create a flow diagram or Datamodel for further implementation. Here is one with which i have created you can design it in your style and in your own way.

For more information on master-detail realtionship and junction object please follow the Link. Junction Object

For creating field in your dev org you have to follow these steps:

Go to setup>search objects than click on the the custom object in which you want to create the field.

Let us go to Course object which you must have created by following the datamodel. Now when we go to our object we will find custom field and relationship extention there now click on the new button.

Now select the type of field which you want to create what we are going to do is to create a lookup field in Course object.

Than you will get a page to select a related to object in which you have to pick your related object in it like i have picked professor as my related to object.

now click next button than write a name and create the field according to the given instructions.

(your field name) > 8

Than save the validation rule. Yipeeee you have created a validation rule.

If you have followed the previous steps correctly than you don’t have to worry at all because you have already done this step.

trigger professorSelectCourse on Course__c (after insert,after update) {

if (trigger.isAfter) // trigger professor can’t have more than four courses

{

set<id> ids=new set<id>();

list<course__c> crList=[SELECT Name,Professor__c FROM Course__c WHERE Professor__c != NULL];

for(Course__c cr: crList)

{

ids.add(cr.professor__c);

}

List<Course__c> profCourseList = [SELECT Name, Id, Professor__c

FROM Course__c

WHERE Professor__c IN: ids

AND Professor__c != NULL];

Map<Id, Integer> ProfCountMap = new Map<Id, Integer>();

for (Course__c course : profCourseList) {

Integer numberOfProf = profCountMap.get(course.Professor__c);

if (NULL == numberOfProf) {

profCountMap.put(course.Professor__c, 1);

} else {

profCountMap.remove(course.Professor__c);

profCountMap.put(course.Professor__c, numberOfProf + 1);

}

}

for (Course__c course : Trigger.new) {

System.debug(‘>>>>>>>>>>>>’ + course + ‘ has ‘ + profCountMap.get(course.Professor__c) + ‘ Professors’);

if (profCountMap.get(course.Professor__c) >= 5) {

course.addError(‘A Professor cannot take more than 4 courses at a time.’);

}

}

} }

For this problem you just need to create a lookup field in class and don’t forget to make it mandatory.

To create an inline vf page first you have to make a controller class which i am sure you must have understood by now by trying the above link. Now our controller is like this:

public with sharing class InlineVfPageProfessorController {

public string Ids{get; set;}

public boolean flag{get;set;}

public InlineVfPageProfessorController(ApexPages.StandardController controller) {

Ids = controller.getId();

}

public List<Student__c> getAllStudents() {

Class__c classId = [

SELECT Id, Name, Class_Teacher__c

FROM Class__c

WHERE Class_Teacher__c =: Ids];

List<Course__c> selectedCourses = [SELECT Id, Name

FROM Course__c

WHERE Class__c =: classId.Id

AND Professor__c =: Ids];

List<Id> CourseListIdList= new List<Id>();

for(Course__c course : selectedCourses) {

CourseListIdList.add(course.Id);

}

List<CourseStudent__c> JunctionObj = [

SELECT Id, Name, Student__c

FROM CourseStudent__c

WHERE Course__c IN: CourseListIdList];

System.debug(‘>>>>>>>>>>>>>>>>>’ + JunctionObj);

List<Id> studentsId = new List<Id>();

for(CourseStudent__c junction : JunctionObj) {

studentsId.add(junction.Student__c);

}

List<Student__c> Students = [SELECT Id, Name, Number_of_Courses__c

FROM Student__c

WHERE Id IN: studentsId];

if (Course__c.Professor__c != NULL){

flag = true;

}

else{

flag = false;

}

return Students;

}

}

This controller will help you finding the students of the professor. Now we have to create the Visualforce page for the controller.

<apex:page standardController=”Professor__c” extensions=”InlineVfPageProfessorController”>

<apex:sectionHeader title=”All student names”/>

<apex:outputpanel rendered=”{!flag}” > These are the students which are teached by teacher. </apex:outputpanel>

<apex:pageBlock >

<apex:pageBlockTable value=”{!AllStudents}” var=”student”>

<apex:column value=”{!student.Name}”/>

</apex:pageBlockTable>

</apex:pageBlock>

</apex:page>

this will do the trick. But we are not done yet now we have show this page in our professors layout. It can be done like this:

Go to your professor object and press on edit link on the page layout section like this:

Now drag a section from here

and drop it any where when it allows you to drop it.

Now type you section name and number of colums you want in your section select it than click ok. Now you have your section to show your page in it.

Now select visualforce pages from the list which will show all the pages you have created realated to that object. Than similarly drag the page you have created and drop into the section you have created jst now.

Yipee now you can see the list of students in the detail page.

Again you can do this by data model. By changing the layout page of the Course object.

Now that you already have edited a layout page i don’t think i have to tell you how to search layout page for Course object so i will do the quick review again go to your object>edit page layout. Thats it you have done it. Now that you are in page layout portion go to its related lists and select related list properties.

Now the field you have created in student with the junction object.

Then add it in selected field list than press ok. Now the student list will be shown in the detail page.

I am sure you know how to  make field now from question number-1.1 these are all just fields that are needed to be formed in Course object.