Introduction to the Exists In Check
The Exists In check asserts that every value in a field also exists in a field on another container. It is the platform's foreign-key rule: use it to keep identifiers, codes, and references pointing at something real.
This section is the complete guide to the check. The Deep Dive covers the definition, properties, and full evaluation semantics, explains how anomalies are reported, walks through production examples, and collects best practices; the How-tos are step-by-step tutorials for creating, editing, and deleting a check; the API page documents the payload for programmatic use; and the FAQ answers the most frequent questions.
Next Steps
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How It Works
The complete reference: definition, field scope, the reference lookup, NULL handling, both filter clauses, and coverage.
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Anomaly Reporting
The anomaly messages the check produces, what the numbers mean, Source Records highlighting, and Custom Anomaly Description.
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Examples
Three production scenarios with sample data, anomaly messages, and the SQL equivalent of what the check evaluates.
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Best Practices
Guidelines for choosing the reference, scoping both sides, and keeping the signal clean.
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Permissions
The team permission each action needs: view, create, edit, archive, restore, and delete.
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Create a Check
Step-by-step tutorial for creating an Exists In check against a reference field.
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Edit a Check
Step-by-step tutorial for changing the reference container or field, or adjusting the filters and coverage.
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Delete a Check
Step-by-step tutorial for archiving a check and deleting it permanently.
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Troubleshooting
Common problems with the reference lookup, NULLs, type mismatches, and anomaly reporting.
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API
Payload shape and field notes for creating an Exists In check programmatically.
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FAQ
Short answers to questions about the reference, NULLs, filters, and anomaly reporting.