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Article #20661: "Operation not applicable" when opening ClientDataSet.

Why am I getting the error "Operation not applicable" when I open a TClientDataset with many master-detail datasets?

There is a limit of 15 master-detail relationships when using nested datasets.

There are two ways you can set up master/detail relationships in client datasets using nested tables.

One is to define them explicitly using the Fields Editor. At design time, right click the client dataset and choose Fields Editor. Add a new persistent field to your client dataset by right-clicking and choosing Add Fields. Define your new field with type DataSet Field. In the Fields Editor, define the structure of your detail table.

A second way that you may not be aware of is to obtain records that contain nested details from a provider component. When a provider component represents the master table of a master/detail relationship, it automatically creates a nested dataset field to represent the details for each record.

Last Modified: 11-OCT-00