Creating a Many-to-Many Relationship is easy in ServiceNow. However...with an example it is even easier!
In this post, I'll show an example "Test Case" Application that has an M2M relationship with "Test Case Steps".
This is a supplement to the wiki article on Creating a Many-to-Many Relationship.
https://wiki.servicenow.com/index.php?title=Creating_a_Many-to-Many_Relationship
Create Test Case Application
1. Create new application (UAT Testing)
UAT Testing Application
2. Create New Table (Test Cases)
Test Case Table
3. Personalize Form (Test Case Form)
Test Case Form Personalize
4. Create New Table (Test Case Steps)
Create New Table (Test Case Steps)
5. Personalize Form (Test Case Steps)
Test Case Steps Form Personalize
6. Turn on Auditing
Test Case Table Turn on Audit
Test Case Steps Table Turn on Audit
Create M2M Relationship between Test Cases and Test Case Steps
1. Go to Many-to-Many Lists (Type sys_m2m.list in the Navigation Filter text)
2. Many-to-Many Lists (Click New)
Many to Many Lists
3. Many-to-Many Lists (Add From and To Tables)
Note: if you add the From and To Tables, the rest will auto-fill in.
Many-To-Many Creation
4. Personalize Related List (Test Cases)
Note: Go to Test Cases and add the Related List: Test Case Steps
Personalize Related Lists (Test Cases)
5. Personalize Related List (Test Case Steps)
Note: Go to Test Case Steps and add the Related List: Test Cases
Personalize Related List (Test Case Steps)
6. Personalize Related List Layout (Test Case Steps)
Personalize List Layout
7. Personalize Related List Layout (Test Cases)
Personalize List Layout
Results
1. Test Case Form
Test Case Form
2. Test Case Steps Form
Test Case Steps Form