Building Custom Relationships in Salesforce: Lookup vs. Master-Detail Relationships

Building Custom Relationships in Salesforce Lookup vs. Master-Detail Relationships by OMI

Custom relationships in Salesforce, particularly master-detail and lookup relationships, offer distinct advantages in managing data and automating processes within the platform. The former establishes a strong bond between two objects, ensuring data integrity; while the latter offers flexibility and scalability, allowing for independent data creation. 


Our OMI team has worked with Salesforce ever since its release and we know all the ins and outs of effective data management. In this article, we’ll share some of our expertise with you – we’ll delve deep into what master-detail and lookup relationships are, their benefits, and practical use cases. On top of that, we’ll look into one more method of connecting data records – junction objects and how to create a junction object in Salesforce.

What Master-Detail Relationships Mean

In Salesforce, a master-detail relationship is understood as a robust and tightly integrated bond between two objects. Within this relationship, one entity assumes the role of the master or parent, while the other becomes the detail or child.


The detail inherits security settings from its master counterpart. Essentially, if you possess viewing, editing, or deleting privileges for the parent’s data, those same permissions extend seamlessly to the child’s data.  The child entity is inexorably linked to its parent; it cannot exist autonomously. Deleting the parent’s data initiates a cascade effect known as a cascade delete, resulting in the removal of all associated child records. 


Moreover, master-detail relationships facilitate the creation of rollup summary fields on the parent entity. These fields serve to automatically aggregate data from its child records, offering invaluable insights through four distinct functions:


  • Count: Providing the total number of child records associated with the parent.
  • Sum: Accumulating the total value of a specified field across the child records, such as the aggregate cost. Utilizing these rollup summary fields empowers organizations to monitor key metrics and performance indicators effortlessly.
  • Max: Identifying the highest value within a designated field among the child records, such as the most expensive cost.
  • Min: Discerning the lowest value within a specified field across the child records, such as the least expensive cost.


Benefits of Using Master-Detail Relationships

The main benefits of master-detail relationships revolve around their robustness, simplicity, and automation, namely:


  • Data Integrity and Consistency: With master-detail relationships, you ensure that child records are tightly bound to their respective master records. For instance, in a scenario where you have a “Job Application” object as the child and a “Job Posting” object as the master, deleting a job posting automatically deletes all associated job applications. This ensures that your data remains consistent and prevents orphaned records, enhancing overall data integrity.
  • Automated Roll-Up Summaries: Master-detail relationships enable the creation of roll-up summary fields on the master record, providing aggregated information from related child records. This automates calculations and provides real-time insights into key metrics without the need for manual data manipulation.
  • Efficient Reporting and Analysis: Master-detail relationships facilitate efficient reporting and analysis by providing a structured data model. In a “Project” master-detail relationship with “Tasks” as child records, you can easily create reports to track project progress, resource allocation, and task completion rates. 
  • Seamless Process Automation: You can automate business processes that span across master and child records. A “Case” master-detail relationship with “Case Comments” as child records will allow you to set up workflow rules to notify support agents when new comments are added to a case. 
  • Streamlined Security Management: By inheriting security settings from the master record, master-detail relationships simplify security management. This ensures consistent access control and reduces the risk of data exposure or unauthorized access.


Use Cases for Master-Detail Relationships

Master-detail relationships are extremely versatile and are not tied to any specific activity or industry:


  • Invoice and Line Items: You can establish a master-detail relationship between an “Invoice” object and a “Line Item” object. The “Invoice” object serves as the master, while the “Line Item” records represent individual products or services included in the invoice. With this relationship, when you create an invoice, you can automatically populate line items, and any changes to the invoice or line items will be reflected in real time.
  • Project and Tasks: For project management, you link a “Project” object to a “Task” object. “Project” is the master, while “Task” records are specific activities or milestones within the project. This way, you can track progress, assign responsibilities, and monitor deadlines effectively.
  • Campaign and Campaign Members: In a master-detail relationship between a “Campaign” object and a “Campaign Member” you can track campaign effectiveness, measure conversion rates, and analyze the impact of marketing initiatives on lead generation and customer acquisition.
  • Service Request and Case Comments: In customer service management, you can create a master-detail relationship between a “Service Request” object and a “Case Comment” object, where the latter represents comments or updates related to service requests. With this, you can track communication history, escalate issues, and provide timely resolutions to customer inquiries.
  • Parent and Child Custom Objects: You can establish master-detail relationships between custom objects to represent hierarchical or dependent data structures. For example, you can create a “University” object as the master and a “Department” object as the child to model the relationship between a university and its academic departments. With this relationship, you can manage enrollment, faculty assignments, and course offerings effectively.


What Are Lookup Relationships

A lookup relationship presents a more loosely coupled connection between objects, distinguishing it from the tighter integration of master details. This implies that the behaviors of the child object are less dependent on the parent entity. Due to this independence, a child object isn’t inherently obligated to have a parent. While it can reference a parent record, it retains the flexibility to exist without one. This flexibility serves as a preventive measure against cascade deletion. 


The autonomy of this relationship extends to security settings as well. Unlike master-detail relationships, where security settings are inherited from the parent, each object in a lookup relationship maintains its security settings independently. This means that the ability to view, edit, or delete a parent object isn’t automatically conferred to the child object, ensuring granular control over data access and modification.


In practical terms, utilizing lookup relationships allows for the creation of more adaptable and scalable solutions, where objects can interact without the rigid constraints of hierarchical dependencies. 


Benefits of Using Lookup Relationships

In contrast to master-detail, lookup relationships benefits are mostly focused on flexibility and scalability:


  • Preservation of Data Integrity: Unlike in some other relationship types, such as master-detail, destroying one item in a lookup relationship does not lead to the automatic deletion of associated records in other objects. This ensures that data integrity is maintained, and associated records remain intact even if a parent record is removed.
  • Scalability: Salesforce allows for a maximum of 25 lookups for a single item, providing scalability for data relationships within the platform. This flexibility allows organizations to manage a diverse range of relationships between records efficiently.
  • Flexibility in Record Creation: In a lookup relationship, the presence of a parent record is not mandatory in the child’s record. This flexibility allows users to create child records independently of parent records, offering greater autonomy in data management.
  • Freedom in Implementation: Lookup relationships offer flexibility in implementation, allowing users to establish connections between objects even if child objects contain no records. 
  • Convertibility to Master-Detail: If all records in the lookup field have values, users have the option to convert a lookup connection into a master-detail relationship. This conversion allows for tighter integration between parent and child records, providing enhanced control and data management capabilities.


Use Cases for Lookup Relationships

Lookup relationships in Salesforce offer versatile solutions for managing data relationships across different objects. Here are some common use cases where lookup relationships prove valuable:


  • Account and Contact Relationships: In many organizations, contacts are associated with specific accounts. By establishing a lookup relationship between the Contact and Account objects, users can easily link contacts to their respective parent accounts. This enables efficient management of customer relationships, allowing users to access contact details within the context of their associated accounts.
  • Opportunity and Product Relationships: Businesses often sell multiple products through various opportunities. A lookup relationship between the Opportunity and Product objects allows users to associate multiple products with each opportunity. This enables sales representatives to track the products associated with each opportunity and analyze sales performance across different product categories.
  • Case and Product Relationships: By establishing a lookup relationship between the Case and Product objects, support agents can easily link cases to the products or services associated with customer inquiries or reported issues. This enables efficient case management and resolution, ensuring that support agents have access to relevant product information when addressing customer concerns.
  • Campaign and Lead Relationships: Marketing campaigns often generate leads that require further nurturing and follow-up. By establishing a lookup relationship between the Campaign and Lead objects, marketers can associate leads with specific campaigns. This allows marketers to track the effectiveness of different marketing initiatives in generating leads and driving conversions.
  • Customizing Data Relationships: Lookup relationships provide flexibility in customizing data relationships based on specific business requirements. Organizations can create lookup relationships between standard and custom objects or between multiple custom objects to reflect their unique data model.


Junction Objects in Salesforce

So what is a junction object in Salesforce? Before we delve into them, we first need to introduce the concept of many-to-many relationships. A many-to-many relationship facilitates the linkage of multiple records from one object to multiple records from another, and vice versa. This relationship model enables versatile data connections between different entities, clearly representing complex interactions within the system.


Managing many-to-many relationships involves the utilization of a junction object, which serves as a bridge between the two related objects. In practical terms, a junction object enables the linking of one custom object or instance to multiple child records, while simultaneously allowing each child record to be associated with multiple parent records. 


To put it simply, a junction object can be likened to a custom object equipped with two master-detail fields. These fields act as the conduits through which connections are established between different records, enabling seamless navigation and manipulation of data relationships within Salesforce. 

Benefits of Using Junction Objects

Now let’s delve into the specific benefits of using junction objects:


  • Efficient Data Management: Junction objects streamline data management by centralizing the management of many-to-many relationships. Instead of creating duplicate records or relying on complex workarounds, junction objects provide a structured approach to managing interconnected data. For example, in a recruitment scenario, a junction object named “Job Application” can link candidates to job openings, facilitating efficient tracking of candidate applications across multiple positions.
  • Automation and Workflow: Junction objects support automation and workflow processes, allowing for the automation of tasks based on changes to related records. For example, in a project management scenario, a junction object named “Task Assignment” can link tasks to team members. Workflow rules can be set up to automatically notify team members when new tasks are assigned to them or when task statuses change, streamlining project execution and collaboration.
  • Data Segmentation and Targeting: Junction objects enable targeted segmentation of data for personalized marketing or communication efforts. For instance, in a marketing campaign scenario, a junction object named “Campaign Member” can link contacts or leads to specific marketing campaigns. This allows marketers to tailor messaging, track campaign engagement, and measure the effectiveness of targeted marketing initiatives.
  • Additional Attributes: Junction objects can include additional attributes or fields that provide context or additional information about the relationship between two objects. These attributes enhance the granularity of data capture and provide insights into the specifics of each relationship.


Use Cases for Junction Objects

Let’s explore some practical use cases where junction objects prove most valuable:


  • Product Bundles: In sales and inventory management, you can use a junction object to represent product bundles or packages. With a “Product” object and a “Bundle” object, we can create a “Bundle Component,” linking individual products to specific bundles. This facilitates accurate inventory tracking, pricing, and fulfillment of bundled products.
  • Membership Subscriptions: A junction object named “Membership Subscription” can link members to the subscription plans they are enrolled in. This allows you to manage membership levels, track subscription renewals, and provide targeted member benefits or services based on their subscription tier.
  • Project Teams: You can use a junction object to assign team members to specific projects. For instance, the junction object named “Project Team” can link employees or users to project records. This enables project managers to allocate resources, track team assignments, and monitor project progress.
  • Vendor Contracts: For procurement and vendor management, a junction object in Salesforce can link vendors to specific contracts or agreements they are party to. This allows procurement teams to track contract terms, monitor vendor performance, and streamline contract renewal processes.
  • Event Attendees: With a junction object such as “Event Attendance” we can link contacts or leads to specific events they are attending. This enables you as an organizer to track attendance, manage capacity limits, and send targeted communications to attendees based on their event preferences or interests.


How to Create a Junction Object in Salesforce

Creating a Junction Object in Salesforce involves setting up a many-to-many relationship between two objects. 


Let’s walk through the process using an example of three objects: Project, Project Task, and Employee, where an employee can be associated with multiple projects and tasks.


  • Step 1: Open your Salesforce Dashboard.
  • Step 2: Navigate to the Quick Search tab and search for “Schema Builder.” Click to open it.
  • Step 3: In Schema Builder, begin by creating your objects. Drag the “Object” element from the left sidebar onto the canvas.
  • Step 4: Create a new object named “Project” and add “Projects” as the plural label. Click “Save” after entering the necessary information.
  • Step 5: Similarly, create another object named “Employee” with “Employees” as the plural label, and “Project Task” with “Project Tasks” as the plural label. Click “Save” after entering the necessary information for each object.
  • Step 6: Once all objects are created, you will see them displayed on the canvas.
  • Step 7: Now, to establish relationships, drag the “Master Relationship” element from the list onto the canvas.
  • Step 8: Create a Master Relationship role related to the “Project” object by connecting it to the “Project” object.
  • Step 9: Similarly, create another Master Relationship role related to the “Employee” object by connecting it to the “Employee” object.
  • Step 10: Your Junction Object is now created. This setup enables many-to-many relationships between employees, projects, and project tasks within your Salesforce dashboard.


Comparing Lookup, Master-Detail, and Junction Relationships

Now let’s compare the three Salesforce properties side-by-side:




Junction (Many-to-Many)

If the master record is deleted, all associated child records are also deleted.



Deleting a parent record doesn’t affect the child records.



Junction objects establish many-to-many relationships between two objects by linking multiple records from each object.


Ensures data integrity by enforcing cascade behaviors such as cascade delete and cascade reparenting.



Does not enforce cascade behaviors. Deleting a parent record does not impact child records.



Does not enforce cascade behaviors by default. Child records remain unaffected by changes to related records.



Supports the creation of roll-up summary fields on the master record to aggregate data from related child records.



Does not support the creation of roll-up summary fields.




Does not support the creation of roll-up summary fields.




Child records inherit security and sharing settings from the master record.



Security settings are set independently for each object.



Security settings are set independently for each object.



Field level security is inherited from the master record.



Field level security is set independently for each object.



Field level security is set independently for each object.



Child records are owned by

the owner of the master record.


Child records can have different owners than parent record.


Child records can have different owners than parent records.



Allows unlimited child records per master record.



Allows up to 25 lookup fields per object.



Can have unlimited records in junction objects.



Supports auto-population of fields on child records from the master record.


Doesn’t support auto-population of fields.


Doesn’t support auto-population of fields.



By discerning the differences between master-detail and lookup relationships, you can strategically leverage their unique advantages to cater to your business requirements. Master-detail relationships offer unparalleled robustness, facilitating automated roll-up summaries and ensuring data integrity through streamlined security management protocols. On the other hand, lookup relationships provide a degree of flexibility and scalability that will allow you to craft adaptable solutions.


Moreover, there are junction objects – invaluable tools for managing complex many-to-many relationships, bridging disparate data entities, and enabling seamless navigation and manipulation of interconnected records. You can count on junction objects in Salesforce to streamline data management processes, automate workflows, and facilitate targeted segmentation for personalized marketing endeavors.


What you can also count on is OMI’s experience of successful Salesforce implementation. So if you are planning to enhance your CRM solution or to implement it from scratch, don’t hesitate to reach out to us – we’ll get it done.


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