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Questionhow to combine column values Pin
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QuestionMany : Many Pin
lost in transition 22-Feb-07 7:05
lost in transition 22-Feb-07 7:05 
I will be describing an electrical system. Option(1) is proposed by someone else, and I proposed option(2). I am using the term 'node' as a point on a electrical bus and 'devices' repersents switches or breakers...

Two option:

(1)(a)1:M<---(b)M:M--->(c)M:1
(2)(a)1:M<===(b)1:M<---(c)1:M

(1)
Table (a)&(c) have a many to many relationship. Table (b) is used to make this relationship.
This is to say that many nodes can connect to many devices. This does not show how different devices might relate to each other nor does it give connectivity. To set up a query to get the rating of a bus can be done with some work.

(2)
Table (a)&(b) have a double one to many and table, meaning the PK of (a) is a FK in (b) twice.
Table (b)&(c) have a one to many.
The (a)&(b) relationship creates a 'section'(Point A to Point B). Then from that a device in table (c) sits on a specific 'section' in which that 'section' is tied to only two nodes
(or records in table (a)). This does give connectivity to the devices and getting the rating of a bus would be much easier.

Option(2) is my opion if one of yall is able to understand what I am presenting. Can I get some feed back on both options. Don't worry I do not get offened by constructive replies. I see how option(1) works but I believe option(2) is more effectent.



God Bless,
Jason

Programmer: A biological machine designed to convert caffeine into code.
Developer: A person who develops working systems by writing and using software.
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AnswerRe: Many : Many Pin
Hesham Amin22-Feb-07 9:55
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GeneralRe: Many : Many Pin
lost in transition 22-Feb-07 11:34
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GeneralRe: Many : Many Pin
Colin Angus Mackay22-Feb-07 13:23
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AnswerRe: Many : Many Pin
Colin Angus Mackay22-Feb-07 13:20
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GeneralRe: Many : Many Pin
lost in transition 23-Feb-07 3:08
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AnswerRe: Many : Many Pin
Marcus J. Smith23-Feb-07 3:52
professionalMarcus J. Smith23-Feb-07 3:52 
QuestionGETDATE Pin
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QuestionDynamic SQL Error Pin
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