How to build "Greater/less or Equal" relationships between two tables?

Question

Hi,
Is there any straightforward approachs to realize the following kind of relationships between two tables?
Table1.process_end_date >= Table2.work_start_date and
Table1.process_end_date <= Table2.work_end_date
BTW, there's no common columns for these two tables to do simple joins (inner, outter...).
Thanks.
Regards,
Qilong 

Answer 1

Sure.
Table.SelectRows filters a given table (in this case Table2) based on a function provided as the second argument.
(table2Row) => is the start of our filter function. It defines a function that takes one argument, called table2Row. Each row of Table2 will be passed to this function. If the function returns true, the row will be kept. If the function returns false,
the row will be filtered out.
The right hand side of the => is the filter expression. Because we're adding the custom column to Table1, we can reference a field in the current row of Table1 using square brackets (e.g. [process_end_date]). To reference the fields in the current row
of Table2, we have to index into the table2Row variable passed to our function (e.g. table2Row[work_start_date]).
Hope that helps.
Ehren