In the table Project Task, the field 'Dependency' which has field type 'Decoration' shows the values (if there are any to show). But when exporting the data via list view into Excel, the column for that field is empty. The values that can be seen in that column won't be there in the column of the excel doc after the export.
This column does not have a value and is calculated and filled in at runtime and is based on the "Planned Task Relationships (planned_task_rel_planned_task)" table. This is why the value cannot be exported or reported on since there really is no value in this field. If we check the show XML, would see that there is no value.
It is a "decoration" type of fields, since it is calculated based on Predecessor and successor and doesn’t actually exist on pm_project_task table.
Dependency information is stored in the Planned Task Relationship [planned_task_rel_planned_task] table. This will give the Predecessor and Successor information.
So we can create a Business Rule on planned_task_rel_planned_task table to update a custom field on the project task with the dependency.
Another Possible way to fetch the dependency task, we can directly refer to planned_task_rel_planned_task table and as per the requirement fetch the details.