Fujitsu UDS/SQL V2.5 사용자 설명서
Schema DDL
OWNER clause and SEARCH KEY clause
U929-J-Z125-9-76
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4.8 Special sets
4.8.1
SYSTEM set
OWNER IS SYSTEM.
A record type which is not related to a higher-ranking record type on the basis of its data
structure can still be declared member of a set.
structure can still be declared member of a set.
This applies in the following cases:
–
For reasons of sequential processing, the records are to be in a different order than
ascending order according to database key values (see
ascending order according to database key values (see
and
ff).
–
In these cases, the record type is declared member of a set which has only a symbolic
owner record type named SYSTEM. Accordingly such sets are called SYSTEM sets.
owner record type named SYSTEM. Accordingly such sets are called SYSTEM sets.
The symbolic owner record type contains exactly one record which is automatically
generated by UDS/SQL. It is called an anchor record. A SYSTEM set thus consists of just
one set occurrence.
generated by UDS/SQL. It is called an anchor record. A SYSTEM set thus consists of just
one set occurrence.
In addition to the possibilities of a normal set, SYSTEM sets allow direct access via hash
routines.
routines.
Defining secondary keys for conversion by hash routine
SEARCH KEY IS item-name,... USING CALC[ hash-routine]
DUPLICATES ARE[ NOT] ALLOWED
DUPLICATES ARE[ NOT] ALLOWED
A key declared by SEARCH KEY IS... is a SEARCH key or secondary key. It may be consist
of more than one item.
of more than one item.
item-name
specifies the item(s) comprising the key. All items must be part of the corre-
sponding member record type.
DUPLICATES ARE[ NOT] ALLOWED specifies whether UDS/SQL is to accept or reject
duplicate key values.
duplicate key values.