What Is Master Detail and Lookup Relationship in Salesforce?

In Salesforce, relationships define how two objects connect and interact with each other. These relationships decide how data is linked, how records behave, and how users can view or manage information inside CRM.

Two of the most important relationship types you must understand are:

• Master-Detail Relationship
• Lookup Relationship

Both help you build data models, automate processes, and create meaningful reports. But they work differently and are used in separate situations. Below is a simple explanation of each, with examples and key differences.

Why Relationships Matter in Salesforce

Salesforce is designed around connected data.

For example:

• A Contact belongs to an Account
• An Opportunity is linked to a Lead or Contact
• A Case is tied to a customer and a product

These connections make it easy to track customer behavior, manage the sales process, and generate meaningful insights.

If you want to understand how Salesforce ties customer experience together, check out this guide on the customer journey in Salesforce. Now let’s explore the two major relationship types.

What Is a Master-Detail Relationship in Salesforce?

A Master-Detail Relationship is a strong, tightly connected relationship between two objects.
One object controls the other.

Master (Parent)

• The main controlling object.

Detail (Child)

• The dependent object.

If the Master record is deleted, the Detail record is also deleted. This is why Master-Detail is used when records must stay linked tightly.

Key Features of Master-Detail Relationship

1. Parent controls child record ownership

The child record doesn’t have its own owner. It takes ownership from the master record.

2. Mandatory relationship

When creating a Detail record, the Master field is required. You cannot save the child record without choosing the parent.

3. Cascading delete

Deleting the Master record automatically deletes the related Detail records.
This prevents orphan records.

4. Roll-Up Summary Fields available

This is one of the biggest benefits of Master-Detail.

You can create roll-up summary fields on the Master object to calculate:

• SUM (total)
• COUNT
• MIN / MAX
  based on values in the child records.

Classic example:

Account (Master) → Invoices (Detail)

You can calculate the total invoice amount on the Account using a roll-up summary.

When Should You Use Master-Detail Relationship?

Use it when:

• Child records must always be connected to a parent
• You need roll-up summary fields
• You want strict control over related records
• Deleting a parent should delete all children

Example:

• Order (Master) → Order Line Items (Detail)

What Is a Lookup Relationship in Salesforce?

A Lookup Relationship is a looser, more flexible relationship between two objects.

Here:

• The child record can exist without the parent
• Deleting the parent does not delete the child
• The relationship field can be optional

This type is used when two records need a connection but not strong dependency.

Key Features of Lookup Relationship

1. No ownership dependency

The child record has its own owner.

2. Optional connection

You can create a record without selecting the lookup field.

3. No cascading delete

If the parent record is deleted, the child record stays.

4. No roll-up summary fields

Lookups do not support roll-ups unless converted to Master-Detail or using automation tools.

5. Multiple lookups allowed

You can create up to 40 lookup fields per object.

When Should You Use Lookup Relationship?

Use it when:

• Child records can exist independently
• You don’t need roll-up summary fields
• You want flexibility
• Deleting a parent should not impact the child

Example:

• Case → Lookup to Product
• Contact → Lookup to Account (in some custom setups)
• Project Tasks → Lookup to Employee

Master-Detail vs Lookup Relationship (Comparison Table)

Feature	Master-Detail	Lookup
Relationship Strength	Strong (dependent)	Loose (independent)
Parent Controls Child	Yes	No
Deleting Parent Deletes Child	Yes (cascading delete)	No (child remains)
Roll-Up Summary Fields	Yes	No
Child Record Mandatory?	Yes – child cannot exist without parent	No – child can exist independently
Security & Sharing	Controlled by parent	Independent of parent
Record Ownership	Child inherits ownership from parent	Child has its own owner
Number of Allowed Relationships	Up to 2 Master-Detail per object	Up to 40 Lookup fields per object
Use in Automation (Flows, Validation Rules)	Parent-child dependency affects logic	More flexible for conditional automation
Best Use Case	When records must stay tightly connected and dependent	When flexibility and independent data structure are required

Real-World Examples in Salesforce

Master-Detail Example

A Property (Master) with multiple Property Units (Detail).
Each unit cannot exist without a property.

Lookup Example

A Case linked to a Contact.
If the Contact is deleted, the Case should not disappear.

How Relationships Affect Reporting

Correct relationships make reporting easier and more accurate.

For example:

• Master-Detail allows roll-up summaries → strong reporting
• Lookup relationships require custom reporting for deeper insights

To improve reporting efficiency, explore more here:
Complete Guide to Salesforce Reports

How Relationships Support Sales & CRM Processes

Relationships help teams manage:

• Leads
• Accounts
• Opportunities
• Support cases
• Custom business processes

In bigger CRM setups, strong data relationships ensure cleaner automation, easier workflows, and more accurate information throughout the Salesforce Sales Cloud.

To understand how CRM structure impacts business performance, you can read:
Salesforce: The Ultimate Guide to CRM Success

Which Relationship Should You Choose?

Choose Master-Detail when:

• The child cannot exist alone
• Parent controls security
• You need roll-up summaries
• You want strict data dependency

Choose Lookup when:

• The relationship is optional
• The child should remain if parent is deleted
• You want flexibility
• You don’t need roll-ups

Conclusion: Understanding Relationships Improves Your Salesforce Data Model

Master-Detail and Lookup relationships are the foundation of Salesforce data architecture.

Choosing the right one ensures:

• Clean data
• Smooth automation
• Accurate reporting
• Better system performance

Whether you are designing a new Salesforce setup or improving an existing one, clear relationships help your CRM deliver better results.