Schema DDL Linking record types
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A record type can be part of several sets. This makes the set the basic unit i n network-like
data structures.
Figure 14: Network-like data structure
Relationships between record types
There are three possible types of relationships between record types that are to be linked:
– 1:n relationship between two record types
– m:n relationship between two record types
– m:n relationship within one record type
1:n relationship
If relationships between records are to be represented in a set, the following r ule must be
observed:
A record may be a member of no more than one set occurrence in a ny set in which it is a
member record, i.e. within a set, a member record is assigned to no more than one owner
record.
An owner record may, however, have more than one member record associated with it.
Thus a 1:n relationship must exist between owner record type and member reco rd type.