2nd post Database design different attributes

[Burghew]

Hi all,

Kindly help me out on this one. I am having a computer shop and we have many
IT related equipments nearly 30 categories which comprises of Servers,
Laptops, PC's, Printers, routers, switches, monitors, Software etc...
Now each of the aboved mentioned category have different attributes such as
Servers may have different configuration like raid, SCSI Hdd, etc, Laptops
may have different attributes from that of PC's, similarly printers, scanner
and monitors have different attributes which are in no way related.

Output needed :
a) To maintain and track all the IT equipment which includes warranty etc
for all the equipments.
b) To check on support/service of equipments when I hand them over for
repair for example.
c) To generate invoices for customers who take or rent stuff from us.

Design
I tried to design this by keeping the following tables
A)
1) tblManufacturers -- Includes all the manufacturer details eg: HP, ACER,
etc
2) tblSuppliers -- Includes all our supplier information.
3) tblAssetCategories -- Includes all the nearly 30 above mentioned eg:
Laptop, Servers, Printers, Monitors, etc.
4) tblCommonAttributes -- Make, Serial No, Warranty Info, Purchasedate,
Purchasecost, etc
5) tblComputer -- Casing, Floppy, USB, MotherBoard, Processor, RAM, etc
6) tblServer -- RaidController, SCSI Type, TapeDrive etc
7) tblLaptop -- battery type, LCD screen type, Touch pad,
8) tblLaserPrinter -- PPM, RAM, trays, etc
9) tblDeskjet -- Catridges details etc.
similarly for the each asset tblRouter, TblSwitch with their attributes.
B)
tblCustomer --contains customer details
tbltransactions --contains details of all the transactions carried out
Related in 1 -- Many -- 1 with AssetID (obtained from the various tables)
C)
tblServiceRelated --- Conatins Items which are under repair/service.
tblScrap -- Items that need to de disposed
I also thought of trying to use One to One relation but that just adds up to
the confusion.

Problem area:
1) How can I link the Primary Key*s* from all the various tables such as
tblComputer which has PK AssetID for every computer
and also from tblLaptops (PK AssetID) , tblMonitors(PK AssetID) ,
tblPrinters (PK AssetID) , etc into the tblTransactions?
Also, I need to have select AssetID when I send them out for service or
to Scrap.

2) If I rent out certain equipment to any customer and if that equipment is
faulty we take it down to repair and assign him another one
till the equipment is fixed and returned and we do not charge him for
that much period for that month. Any Ideas please.

Please do let me know if my approach is correct and if any changes need to
be done. Awaiting eagerly for your replies thanks in advance.

 

[Jeff Boyce]

Burghew

Something to consider ... (and you didn't mention how tables of equipment
type are related)

Since each of the different types of equipment have both common and unique
attributes, you could use one table to "register" all of them, and your
tblLaptop, tblDesktop, tblLaserPrinter tables to further define them. I
believe this would also allow you to register the same type of equipment
from different manufacturers.

The equipment-attribute tables would use the Primary ID from the main
(register) table as their (non-autonumber) Primary ID. This would represent
a 1:1 relationship.

With this design, you don't have to look to multiple tables to find the ID
for your Transactions -- you just use your tblEquipment (register/common
attributes) table's ID, and a "type" field. You also use this to know which
of the specific tables to look to for specific attributes.

As for an approach to record the "bookings" (equipment-to-customer), do you
have a yes/no field related to "Billable"?