When you create a new Field in Messaging, you provide a user-friendly display name for the Field. The platform automatically creates a system version of the display name by replacing spaces with underscores, and putting the name in all lower-case. The system version of a Field name is referred to as the "Column Name." For example, a Field with a display name of "Order Number" would get a system-generated Column Name of "order_number."
The Column Name can be found on the Tables screen. In the list of fields within a selected table, the Column Name is displayed along the right-hand side of the screen.
You can also retrieve the Column Name using the Table API endpoint:
Submit a request to the Table API endpoint. The simplest method is to use the version of the Table endpoint that allows you to retrieve table information based on the Table Name (see How to Find the Table Name if you need help finding the Table Name).
Within the API response message, the system lists every field in this table. As part of that field definition, the response includes the Column Name (referred to as the "columnName").
Sample Response:
{
"viewId": 1002,
"entityId": 100,
"displayName": "Create Date",
"propId": 1030,
"columnName": "create_date"
}