create relationships before or after data import??

[d²c]

Hi there,

When I design my database and create some relationships between tables, should I do this before or after importing data?

If I already have data in my table, will the relationship be made properly when I insert data in another table?

Tnx in advance for the help,

greetz

[Kent Searight]

It all depends on what you expect the relationship to do.

Can you be a little more specific...maybe tell us what your database is for and the perspective(s) from which you'd like to view your data?

[T-Square]

My simple recommendation would be to create the relationships first. My reasoning for this is that you can set up your interface to use the relationship to automatically insert the related ID into your child record, but only if the relationship is there already. This means that any new records that get added through the interface will get the correct ID as they are created.

As for importing records, if the respective ID numbers are in the right places (Note: this can be a BIG if!), then the relationship will be "made" correctly. A relationship just tells the software that "If I am looking at Purchase Order #17, please show me all the LineItem Records that have 17 in the fkPurchaseOrderID field."

Looked at this way, it doesn't matter what the match fields are, or how they arrived at their content--it just matters that they match.

Now, the big IFs: when you import into your tables, your parent ID has to get into your child records. This is no big deal if they're already there (for example, you're upgrading an older database). But if you're creating new ID numbers in the parent table, then you have to find a way to get that ID into the right field in the child records.

HTH,

David