TurboIMAGE/XL Database Management System Reference Manual (30391-90012)

40 Chapter2
Database Structure and Protection
Data Set Types and Relationships
Automatic and Manual Masters
A master data set is defined as either automatic or manual. The characteristics of both are
described below:
In Figure 2-3., CUSTOMER is a manual master data set, and DATE-MASTER is an
automatic master data set. Before the SALES entry for account 12345678 is added to
SALES, CUSTOMER must contain an entry with the same account number. However, the
DATE-MASTER entries for DATE equal to 910927 and 910928 are automatically added by
TurboIMAGE/XL when the detail entry is added to SALES unless they are already in the
DATE-MASTER data set.
DATE-MASTER, an automatic master, contains only one data item which is the key item
DATE. CUSTOMER, a manual master, contains several data items in addition to the key
item.
If the SALES entry with account number 95430301 and stock number 35624AB3 are
deleted, and no other SALES entry contains a PURCH-DATE or DELIV-DATE value of
910905, the DATE-MASTER entry with that value is automatically deleted by
TurboIMAGE/XL.
Table 2-1. Manual and Automatic Masters
Manual Master Automatic Master
Can be standalone (not related to any detail
data set) or can serve as an index for one or
more detail data sets.
Must serve as an index to one or more detail
data sets.
Must contain a key item and can contain other
data items.
Must contain only one data item, the key item.
The user must explicitly add or delete all
entries. A related detail data set entry cannot
be added until a manual master data set entry
with matching key item value has been added.
When the last detail entry related to a master
entry is deleted, the manual master entry still
remains in the data set. Before a master entry
can be deleted, all related detail entries must
be deleted.
TurboIMAGE/XLautomaticallyaddsordeletes
entries when needed based on the addition or
deletion of related detail data set entries.
When a detail entry is added with a search
item value different from all current key item
values, a master entry with matching key item
value is automatically added. Deletions of
detail entries trigger an automatic deletion of
the matching master entry if it is determined
that all related detail entries have been
deleted.
The key item values of existing master entries
serve as a table of legitimate search item
values for all related detail data sets. A
nonstandalone manual master can be used to
prevent the entry of invalid data into the
related detail data sets.