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Schema Map

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In this lesson, you will learn:

  • What a schema map is
  • How to open one for any table
  • How to read the boxes and lines

1 A map of your tables

By now you know tables extend other tables, and reference other tables. That’s a lot to keep in your head! A schema map draws it for you. 🗺️

Key term: Schema map

A diagram that shows a table, the tables it extends or is extended by, and the tables it references or is referenced by.

2 Opening a schema map

  1. Go to System Definition > Tables.
  2. Open a table, like Incident.
  3. Under Related Links, click Show Schema Map.
A schema map for the Incident table. Incident is in the middle. Above it, Incident extends Task. Around it, reference lines go to User through Caller, to Group through Assignment group, to Configuration Item through Configuration item, and to Problem through Problem. A legend shows that one line style means extends and another means references.
Figure 1. The schema map shows how Incident connects to other tables.

3 Reading the map

You see It means
Box A table, with its fields listed inside
Line to a parent This table extends the parent, like Incident extends Task
Line labeled with a field A reference, like Caller pointing to User
  • Use the checkboxes on the side to show or hide extended, extending, and referenced tables.
  • Drag boxes to tidy the picture. Double-click a box to open that table’s map.

💡 Good to know: Schema maps are great before you build. Check what already exists so you don’t create a table or field that’s already there.

⭐ Remember: System Definition > Tables > open a table > Show Schema Map.

4 Let’s try it: map your table

  1. Open the schema map for Incident. Find Task above it.
  2. Find the line for Caller. Which table does it point to?
  3. Now open the schema map for your Room Booking table from Lesson 29.3. What does it extend?

5 Quick recap

  • A schema map draws a table’s connections
  • It shows extends (parent and child) and references
  • Open it from a table record’s Show Schema Map link
  • Use it to plan before you build

6 Check yourself

Think of your answer first. Then tap to check.

1 Where do you find the Show Schema Map link? Show answer

On a table record in System Definition > Tables, under Related Links.

2 Name the two kinds of connections a schema map shows. Show answer

Extends (parent and child tables) and references.

3 On Incident’s map, which table does the Caller line point to? Show answer

User (sys_user).

Nice work! You finished this lesson. 🎉

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