AXEL Relationship Functions

AXEL provides powerful relationship traversal features that allow you to work with data across multiple related forms. These functions enable you to follow relationships between records, aggregate data from related tables, and filter or group data based on related fields.

Overview

In Mars, forms can have relation fields that link to other forms. For example:

• An Orders form might have a customer field linking to Customers
• A Customers form might have a region field linking to Regions

AXEL's relationship functions let you traverse these connections to access data from related records.

Quick Reference

Feature Matrix

When to Use Each Feature

Use RELATED when you need:

• A single column value from a related record
• To add a column showing related data (e.g., customer name on orders)
• To filter by a related field's value
• To group results by a related field

Use RELATEDTABLE when you need:

• All matching records from a related table
• To count or sum values from multiple related records
• To aggregate data from a one-to-many relationship

Use VIA when:

• The relationship field name differs from the table name
• You need to traverse multiple relationship hops
• You want explicit control over the traversal path

Use JOIN: INNER when:

• You want to exclude records without relationships
• You're calculating aggregates and want to skip orphans
• NULL values would skew your results

Use DEFAULT when:

• You want a meaningful fallback for orphan records
• You're displaying data and need user-friendly values
• You want "Unassigned" or "Unknown" instead of blanks

Data Model Example

Throughout this documentation, we'll use this example data model:

┌─────────────┐     ┌─────────────┐     ┌─────────────┐     ┌─────────────┐
│   Orders    │────>│  Products   │────>│ Categories  │────>│ Departments │
│             │     │             │     │             │     │             │
│ - amount    │     │ - name      │     │ - name      │     │ - name      │
│ - quantity  │     │ - price     │     │ - discount  │     │ - budget    │
│ - date      │     │ - stock     │     │             │     │             │
│ - product   │     │ - category  │     │ - department│     │             │
└─────────────┘     └─────────────┘     └─────────────┘     └─────────────┘
        │
        │
        v
┌─────────────┐     ┌─────────────┐
│  Customers  │────>│   Regions   │
│             │     │             │
│ - name      │     │ - name      │
│ - email     │     │ - manager   │
│ - region    │     │             │
└─────────────┘     └─────────────┘

Learn More

Explore each feature in detail:

• VIA Clause - Learn how to traverse single and multi-hop relationships
• JOIN and DEFAULT Options - Handle orphan records gracefully
• RELATEDTABLE Function - Work with multiple related records
• Cross-Table Operations - FILTER, SUMMARIZE, and aggregations with relationships

Quick Examples

Get customer name for each order

ADDCOLUMNS(
  [Orders],
  "Customer Name", RELATED([Customers][name], VIA(customer))
)

Get region name (2-hop traversal)

RELATED([Regions][name], VIA(customer, region))

Count orders per customer with fallback

ADDCOLUMNS(
  [Customers],
  "Order Count", COUNTX(RELATEDTABLE([Orders], VIA(customer)), 1)
)

Filter orders by region

FILTER(
  [Orders],
  RELATED([Regions][name], VIA(customer, region)) = "North America"
)

Revenue by department (3-hop aggregation)

SUMMARIZE(
  [Orders],
  RELATED([Departments][name], VIA(product, category, department)),
  "Total Revenue", SUMX([Orders], [amount])
)