Each CA-IDMS
database consists of database records that are grouped into
record
types. A
record type consists
of the record's name, all of its elements, and the elements' attributes,
such as data types and sizes. These record types are linked together
through different logical groups called sets. Sets are defined to
the schema.
A
set is
a logical relationship established between two or more named record
types. One record type is the owner of the set and the other record
types are members. Record types can belong to more than one set, so
a record type can be both an owner of one set and a member of another.
That same record type can also be a member of more than one set.
These sets and their interweaving relationships make up a
network and
give CA-IDMS its network capabilities.
To move through
the database, each record type contains pointers to other record types
in its set or sets.
Pointers identify
the next record in the set and link the records together in a chain.
There are three types of pointers:
Next pointer (required pointer)
points to the next
record type in the set, regardless of whether the record type is an
owner or a member of the set.
Prior pointer
works the same way
as the Next pointer except that it points to the prior record type.
Owner pointer
points from a member
record type to the owner record type.
Through these pointers,
a program can navigate through the network and travel a specific path
through one or many sets.
The database administrator
is responsible for defining record types and sets in the schema.