# Standard objects, relationships and Schema Builder

*Platform Administrator Study Guide · Object Manager and Lightning App Builder · Last updated October 16, 2026 · https://www.certifyforce.com/study-guide/platform-administrator/object-manager-and-lightning-app-builder/standard-objects-and-relationship-types*

How standard and custom objects connect through lookup, master-detail, junction and hierarchical relationships, what each relationship does to deletion, ownership, sharing and roll-ups, and where record types and Schema Builder fit in the data model.

- Certification: Salesforce Platform Administrator
- Exam section: Object Manager and Lightning App Builder
- Study guide: https://www.certifyforce.com/study-guide/platform-administrator

**Official exam objective:**

> Describe the standard object architecture and relationship model (for example: standard object, parent/child, master detail/lookup/junction relationships, record types, Schema Builder).

## What the exam expects

- Recognise when a delivered standard object or standard junction (Opportunity Contact Roles, Campaign Members) already meets a requirement, before building a custom object.
- Choose between lookup, master-detail, many-to-many (junction), hierarchical and external relationships from requirements about deletion, ownership, sharing, required values and roll-ups.
- Predict the effects of changing a relationship: converting lookup to master-detail and back, enabling reparenting, and the per-object relationship limits.
- Explain how record types present different picklist values, business processes and page layouts on the same object.
- Use Schema Builder to view and build objects, fields and relationships, and know what it cannot do.

## Key facts

| Fact | Detail | Source |
|---|---|---|
| Default lookup delete behaviour | Clear the value of this field | [Relationships Overview](https://help.salesforce.com/s/articleView?id=platform.overview_of_custom_object_relationships.htm&type=5) |
| Delete this record also | Custom lookup on a custom object only; disabled until Salesforce enables it | [Relationship Considerations](https://help.salesforce.com/s/articleView?id=platform.relationships_considerations.htm&type=5) |
| Reparenting detail records | Blocked unless Allow reparenting is selected | [Relationships Overview](https://help.salesforce.com/s/articleView?id=platform.overview_of_custom_object_relationships.htm&type=5) |
| Lookup to master-detail | Every record must have a lookup value | [Relationship Considerations](https://help.salesforce.com/s/articleView?id=platform.relationships_considerations.htm&type=5) |
| Master-detail to lookup | Blocked while roll-ups exist on the master | [Relationship Considerations](https://help.salesforce.com/s/articleView?id=platform.relationships_considerations.htm&type=5) |
| Junction primary relationship | First master-detail created; drives look, owner and division | [Relationship Considerations](https://help.salesforce.com/s/articleView?id=platform.relationships_considerations.htm&type=5) |
| Schema Builder cannot add | Geolocation fields | [Schema Builder](https://help.salesforce.com/s/articleView?id=platform.schema_builder.htm&type=5) |

## Check yourself

- Which lookup delete option is the default, and which one requires Salesforce to enable it?
- When can a lookup relationship be converted to master-detail?
- Which relationship on a junction object determines the owner its records inherit, and how is it chosen?
- Why does a campaign need Campaign Member rather than a lookup or multi-select picklist to track who responded?
- Why must a third parent reference on a junction object be a lookup?

## Sources

- [Object Relationships Overview](https://help.salesforce.com/s/articleView?id=platform.overview_of_custom_object_relationships.htm&type=5)
- [Considerations for Object Relationships](https://help.salesforce.com/s/articleView?id=platform.relationships_considerations.htm&type=5)
- [Design Your Own Data Model With Schema Builder](https://help.salesforce.com/s/articleView?id=platform.schema_builder.htm&type=5)
- [Create Record Types](https://help.salesforce.com/s/articleView?id=platform.creating_record_types.htm&type=5)
- [OpportunityContactRole (Object Reference)](https://developer.salesforce.com/docs/atlas.en-us.object_reference.meta/object_reference/sforce_api_objects_opportunitycontactrole.htm)
- [CampaignMember | Object Reference](https://developer.salesforce.com/docs/atlas.en-us.object_reference.meta/object_reference/sforce_api_objects_campaignmember.htm)

## About the full unit

The "Core concepts", "Exam traps" and "Worked scenario" sections of this unit, its 17 linked practice questions, and unlimited timed mock exams are included with the Platform Administrator pack (USD $19): https://www.certifyforce.com/practice-exams