Guillaume Saumure wrote:
I have to create a small program to track changes done on multiple
machines. The data structure look like :
Structure Notice
PrimaryKeyID.l
Type.l
Date.l
ExecutedBy.s
RequestedBy.s
Description.s
EndStructure
Structure Machine
PrimaryKeyID.l
Name.s
Location.s
List Notices.Notice()
EndStructure
To make a long story short, I have a Linked list nested inside Linked
list but I really don't know how to manage a scenarios like this using
Database recording system. Any suggestions ?
If I understand your "Linked list" and "nested" terminology as you
intend, it could be recast in data modeling terms this way:
1. There is a set of Machine objects.
2. With each Machine object there is an associated set, possibly empty,
of Notice objects.
The way to represent this in a database is to have a foreign key in the
table representing Notice objects, where its value for each row refers
to the Machine object, by its ID, with which it is associated. So, your
Notice table definition would have a column definition such as:
MachineID as integer references Machines(ID)
Your List structure has ordering in addition to defining sets. If you
wish to retain the order of the Notice object in the database, there
will need to be a column in the Notices table giving its sequence number
within the set which can be used to recreate the ordering in a query.
Regards,
--
Larry Brasfield
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