relating tables vs. join during query

[miconian]

Is there a difference between:

a) Creating a relationship between two tables, and then running a query that involves them both.

b) Taking two previously unrelated tables, running a query that involves them both, and creating a join within the query that connects them.

Or are these effectively the same thing?

 

[xenou]

In terms of running queries, I find in practice they are the same thing.

In terms of database design, creating joins is useful if you want to set up referential integrity (i.e., [PODetail] must have a parent record in [POHeader] and so on). So that might be a very big difference.

Otherwise, you may find it marginally beneficial to create the relationships even without referential integrity so that when you create queries the relationships are already established. Especially when you start having joins with three or four tables in them, and they're all ready to go as soon as you add them to the query designer grid, this can make life a little easier. Even more so if you constantly have to un-join the wrong fields that Access is attempting to join for you (with autojoin, if you have it on). How do I know this ... well, Don't ask.

ξ

 

[miconian]

Thanks, that's helpful.