Initializes a System.Data.IDbCommand object to set the 'External Store' token that corresponds to the sopInstanceUid.
command
Type: System.Data.IDbCommand The database command that will be initialized to execute the query.
sopInstanceUid
The SOP Instance UID that identifies the instance
If there is no corresponding Leadtools.Dicom.DicomDataSet that exists on the 'External Store', the token returned is the empty string.