The hierarchy property is unusual in that it contains an array of a second property. Typically, if you assign multiple values to a property, EGL recognizes only the last assignment. Use the hierarchy property to define as many @relationship complex properties (see @relationship) as you need to define the structure of your hierarchical database, as in the following example:
hierarchy = [@relationship { segmentRecord = "CustomerRecordPart" },
@relationship {
segmentRecord = "LocationRecordPart", parentRecord = "CustomerRecordPart" },
@relationship {
segmentRecord = "OrderRecordPart", parentRecord = "LocationRecordPart" },
@relationship {
segmentRecord = "ItemRecordPart", parentRecord = "OrderRecordPart" },
@relationship {
segmentRecord = "CreditRecordPart", parentRecord = "CustomerRecordPart"},
@relationship {
segmentRecord = "HistoryRecordPart", parentRecord = "CustomerRecordPart" }]
For a complete example of a PCB record, see Example DL/I database.
Type: @relationship