The schema is the physical arrangement of the data as it appears in the DBMS. The subschema is the logical view of the data as it appears to the application program.
Latest Answer : Schema : RePresents the complete desription of the databasesubschema - subset of schema,application view of the idms db ...
A record occurrence is the instances of a record; it is the smallest addressable unit of data. A type is the description of a record; there need not be any occurrences.
In local there is no IDMS System running above the DBMS. It is the more efficient mode but lacks the recovery and integrity facilities of the central version (CV) control program. In CV many application
A junction record is a member record type that allows for many-to-many relationship between its two owner records. For a school database the CLASS record is a junction for the TEACHER and SUBJECT record
A set is an owner record and, optionally, its member records. There are three types of pointers: next, prior and owner, but only next is required. There are five possible orders for arrangements of sets;
Latest Answer : A.By Codasyl conception SET is data chain between Owner and Member record. B.Pointers: NEXT,PRIOR,OWNER(direct adresation to OWNER_RECORD from MEMBER).At least NEXT pointer is requered to navigate via set.C. Number of sets really is unlimited. ...
The old joke - where the programmer thinks he is, but the DBMS knows he is not. Currency is the location within the database during run-unit execution. There are four levels of currency: current of run-unit
Locks may be shared or exclusive. Shared means that other run units can retrieve the record but can not modify it. Exclusive means that other run units can neither retrieve nor modify it. Record locks
Find tells you whether the record is actually in the database. If it is not found you save the overhead of an obtain.
When you are obtaining next within a set and get a end of set return code, on what record are you now current?
You are current on the owner.
No. The mode is specified via the SYSCTL DD card in the JCL.
