Defining lists in database tables.

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Hi folks, A quick query on database design here....

I'm building a personal site which lists farms in Australia with details about the farm.

I'd like to set it up so that I can not only identify a primary crop associated with that farm, but that a list of secondary crops can be identified also.

Now I've read a fair bit so I have the basics of design down (sort of). I know about primary and foreign keys and how I would go about setting up and associating the tables for primary crop and the farm. I just can't seem to get my head round how I would set up the other.

I would be using Guids to identify each crop.

Do I just assign the row to the nvarchar(max)then add a comma-delimited string with a list of the crop Guids?

Any input would be most welcome.

Cheers

Posted 27-Apr-10 0:05am

JimBob SquarePants

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Saurabh.Garg · Accepted Answer · 2010-04-27T00:12:00

You will need two tables to do this.

First table:
FarmID, PrimaryCropGuid, other fields.
FarmID is the primary key.

Second table:
FarmID, SecondargCropGuid.
FarmID is the foreign key pointing to the FarmID in first table.

Now if you want all secondary crops of a given farm then you can do:

SQL

SELECT SecondargCropGuid from SecondTable WHERE FarmID='GivenID';

You can also find all farms which grow secondary crops with:

SQL

SELECT FarmID from SecondTable WHERE SecondaryCropGuid='GivenGuiD';

-Saurabh