Analyzing table relationships

Release version: Zurich

Updated July 31, 2025

2 minutes to read

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Summary of Analyzing table relationships

The schema map feature in ServiceNow provides a visual representation of a selected table and its related tables, helping you understand table relationships within your instance. The selected table is highlighted in yellow and centered, with related tables displayed around it. This visualization aids in navigating complex data structures by showing how tables connect and interact.

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Key Features

Relationship Controls: Use check boxes to filter which relationship types are shown, enabling focused analysis of specific table connections.
Relationship Indicators: Colored bars and connector lines visually represent the nature of relationships between tables. Hovering over connector lines displays detailed relationship information.
Table Selector: A list view allows quick navigation by clicking table names to center them in the map. You can also hide or show tables using eye icons and pin the selector for persistent visibility.
Context Menu Actions: Right-clicking a table node offers options to refocus the schema map on a different table, view the table’s record list, or access its system dictionary.
Visibility Controls: Related tables can be hidden or shown to declutter the map, with easy toggling through the table selector.
Derivation Hierarchies: For tables in derivation hierarchies, expand nodes to include their full hierarchy, helping understand inheritance relationships between tables.
Column Details: Expand columns in the schema map to see table fields and their reference targets. Columns from extended tables are displayed in reverse derivation order, clarifying inherited data fields.

Practical Benefits for ServiceNow Customers

Using the schema map to analyze table relationships enables you to:

Quickly visualize and explore how tables relate, improving understanding of your data model.
Navigate complex table hierarchies and inheritance structures efficiently.
Access detailed dictionary and record information directly from the visualization for faster troubleshooting and configuration.
Customize views to focus on relevant relationships, reducing complexity and enhancing clarity.

This tool is essential for administrators and developers who need to manage, extend, or troubleshoot ServiceNow data models effectively.

The schema map shows the selected table in yellow, typically centered, and all tables related to that table, typically shown at the sides.

From this map:

The check boxes at the top allow you to control which relationships to display. Select or clear a relationship type to display or hide tables with that relationship to the selected table.
Each related table has a colored bar indicating the relationship to the selected table.
You can point to the connector lines to display the details of a relationship between the two tables.

Note:

Since relationships are shown as single lines for simplicity, the diagrams rendered are not entity relationship diagrams.

Using the Table Selector:

To view a schema map as a list, point to the table selector in the right corner: List view of tables.

You can:

Click a table in the list to scroll the schema map to that table.
Click the eye icon beside a listed table to hide or show that table in the schema map.
Click the pin icon in the selector to keep the list open.

Using Related Tables:

Right-click a table node header to display a context menu with these functions:

Focus on this table: Make the selected table the new focus table and redraw the schema map based on the new selection.
The new focus table is added as a breadcrumb at the top, allowing you to return to the previous table at any time.
Go to list: Display the list of records for the table.
Go to dictionary: Display the system dictionary, filtered for the selected table.

To hide a related table from view, click the eye icon in the node header (the node can be made visible again with the table selector).

For tables that are part of their own derivation hierarchy, click the expand button (+) in the node header to add their derivation hierarchy to the schema map.

Viewing More Information

Click the expand button (+) beside Columns to expand the table fields.

Expanded view of tables.

The reference fields show a red notation of the table they refer to.

If any tables extend from a table, their columns are displayed in reverse derivation order. For example:

Server is derived from Computer, which is derived from Hardware, which is derived from Configuration Item.

Here, the Server [cmdb_ci_server] table extends from Computer [cmdb_ci_computer], Hardware [cmdb_ci_hardware], and Configuration Item [cmdb_ci], and displays the columns from those tables.

Similarly, the Computer table displays the columns from the Hardware and Configuration Item tables.