Antw: many-many mapping between unique tables

>>> Indraneel Majumdar <indraneel@www.cdfd.org.in> 16.10.2000  20.11 Uhr >>>
> Hi,
>
> I am facing a problem in mapping between two tables containing unique
> entries
>
> T1        T2
> _________    ________
> |  x1    |    |  y1    |
> |  x2    |    |  y2    |
> |  x3    |    |  y3    |
> ---------    ---------
>
> x(i) points to 1 or more entries in T2. y(i) points to one or more entries
> in T1. How do I store this mapping? I'd cannot use an array due to size
> restrictions and inability to extract data easily for furthur processing.
> 
> I don't want to put everything into a single table and repeat values in
> the 2nd column since these are really huge tables and I cannot increase
> overhead by increasing data redundancy.
> 
> Is there some way to do something about this?
>
> \Indraneel
> 
> /************************************************************************.
> # Indraneel Majumdar                  ¡  E-mail: indraneel@123india.com  #
> # Bioinformatics Unit (EMBNET node),  ¡  URL: http://scorpius.iwarp.com  #
> # Centre for DNA Fingerprinting and Diagnostics,                         #
> # Hyderabad, India - 500076                                              #
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I'm not sure if I understand your question. Is it right, that the x(i) are different values
of an column x in table T1 and the y(i) are different values of an column y in table T2?
And you want to have a n:m relation between the two tables?
Then you need a third table T12 with columns x and y, that contains one row for each
mapping of a x(i) with a y(j).

I hope this helps.


Gerhard