Contact custom records - display only record with latest date or just one if date blank

Summary

Return single latest customer record for a contact

Content

Our contacts have custom records in eg. myTable.

They may have none, a single, or multiple linked records in myTable. They may even have multiple records with myTable.startDate blank.

We only want the latest myTable.startDate row to display. I have tried putting max(myTable.startDate) in the column definition but that didn't seem to have any effect.eg. what it currently looks like is below but I want it to end up with a single row per contact,

contact       startDate

100001       12-Mar-20

100002     

100002  

100002        04-Apr-20

100002        09-Apr-20