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  1. #1
    Join Date
    Jul 2004

    Unhappy help on computer usage data design

    i need to normalize and make a ERD for 3 seperate tables in excel
    the 3 tables r: workstation, monitor and printer
    for each table it hv the following

    workstation (user name, department, model, S/N#, code, installed software list)
    monitor (user name, dept. model, S/N#, code)
    printer (user name, dept. model, S/N#, code)

    as not every ws/mon/printer has its own code or S/N#
    so i plan to use the user name and dept as primary key and alter. key

    however i am not sure how should i relate them and what should i do w/ the software list

    the list is sth like (Eng. Windows 2000, Office 98, Winzip, Norton...)
    how can i normalize it?

    would anyone plz kindly help me on this
    any reply is gd for me

  2. #2
    Join Date
    Sep 2002
    You would normalise the software list by creating another table like this:

    create table workstation_software
    ( ws_key ...
    , software_name ...
    , primary key (ws_key, software_name)
    , foreign key (ws_key) references workstation

    Here "ws_key" means whatever column(s) form(s) the PK for workstation.

    Actually, software probably deserves a table of its own, so that you have something like:

    create table software
    ( software_code varchar2(10) primary key
    , software_name varchar2(60) not null unique

    create table workstation_software
    ( ws_key ...
    , software_code varchar2(10)
    , primary key (ws_key, software_code)
    , foreign key (ws_key) references workstation
    , foreign key (software_code) references software

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