Salesforce is built around objects and data relationships. To get the most out of the platform, itâs important to understand how different objects can relate to each other. In this guide, weâll walk through the three main types of object relationships in Salesforce: Lookup, Master-Detail, and Many-to-Many.
Whether you’re just starting out or looking to tidy up your org’s data model, this will help make things clearer.
Lookup Relationships
A Lookup Relationship is a simple connection between two objects. Itâs like saying, âThis record is related to that one,â but they donât depend on each other.
Example:
You might have a custom object called Project__c and another one called Employee__c. You can create a Lookup field on the Project object to link it to an Employee â showing which employee is responsible for that project.
- Records can exist without being linked
- Deleting one record doesnât delete the related one
- Good for flexible, non-dependent relationships
Master-Detail Relationships
A Master-Detail Relationship is more tightly connected. One object is the âmasterâ and controls certain behaviours of the âdetailâ object.
Example:
You might have Invoice__c (master) and Invoice_Item__c (detail). Each item must belong to an invoice. If the invoice is deleted, all its items are deleted too.
- The detail record canât exist without the master
- The master record controls sharing and permissions
- Roll-up summary fields can be used (e.g. total invoice amount, total number of items)
This is perfect when you want dependent data that shouldnât stand alone.
Many-to-Many Relationships
Sometimes, one record needs to be related to many records, and vice versa. Thatâs where Many-to-Many Relationships come in.
Salesforce handles this by using a junction object – a custom object that connects the two.
Example:
Letâs say you have a Student__c object and a Course__c object. A student can take many courses, and a course can have many students. You create a Course_Registration__c junction object with two master-detail fields – one to Student, one to Course.
- Enables complex relationships
- Gives visibility from both sides
- Common in education, HR, and inventory management use cases
Summary Table
| Relationship Type | Dependency | Record Deletion | Roll-Up Fields | Use Case |
| Lookup | No | Independent | No | Flexible link between records |
| Master-Detail | Yes | Detail deleted with master | Yes | Strong data dependency |
| Many-to-Many | Yes (via junction object) | Controlled by master-detail rules | Yes | Link multiple records to each other |
Final Thoughts
Choosing the right relationship depends on your data structure and how closely records should be connected. A well-thought-out object relationship setup makes reporting, automation, and user experience far smoother.
Need help designing your Salesforce data model or relationships?
At IntegraLogic, we specialise in creating clean, scalable Salesforce solutions tailored to your business. Drop us a message – weâre happy to help!