The following example shows how to use [_THISROW-n] to access columns in child and grandparent records. See also Use Start expressions in templates.
Template
The following template example filters the Grandchild records based on a condition that is determined using a value in the Child row. Let’s assume we have a number column[Top] in the Child table that determines how many Grandchild records to select.
<<Start: [Related Children]>> <<[Child]>>
| ID | Created | ParentID/ChildID | Child |
<<Start: SELECT([Related Grandchildren][ID],[OrderNumber]<=[_THISROW-1].[Top])>><<[ID]>> |
<<[Created]>> |
<<[ChildID]>> |
<<[Grandchild]>><<End>> |
<<End>>
Result
Note that the SELECT() expression is using [_THISROW-1] to reference the Top column in the Child table. If you use [_THISROW], it would refer to the Top column in the Parent table, which doesn’t exist.