Overview
The nested dataset feature of ClientDataSet is used to solve the Master-Details design pattern in which a TDataSet field is inserted into the column list. This feature has always been considered a magical technique.
However, the core of database technology is still SQL, so let's take a look at how Delphi uses SQL to pull data in the nested dataset mode.
Surprisingly, the way to pull data is to fetch all details to the client-side at once when fetching data from the header.
