If you have a CraneType column in the master table then you could use
that to determine which other table has associated data for that
Crane. i.e. if CraneType = "ROUGHTERRAIN" then look in the RoughTerrainCrane table.
> Date: Tue, 29 Jan 2008 10:04:26 -0800 > From: email@example.com > To: firstname.lastname@example.org > Subject: RE: Determine which child table a record belongs to > > > Thanks for your help, Brad. You are absolutely right. In this case, it > doesn't make sense to have so many tables. I will make the changes you > suggest. However, there are times when it does make sense to have this kind > of hierarchical structure such as when the child tables have different > fields, so my question remains: How would I determine which of the child > tables the key belongs to without querying each child table? I appreciate > any further assistance. > > Again Thanks, > Tricsta > > > Brad Moore wrote: > > > > Can I suggest changing the "Crane" table to include a CraneType column or > > something similar? I don't know if there is a reason that's not obvious > > to me why you need all of the other tables. It looks like you're using > > the other tables to determine the type of crane, the same thing could be > > done with one additional column in the Crane table. That would simplify > > your database design a lot. Unless I'm missing something. > > > > Brad > > > > > > -- > View this message in context: http://www.nabble.com/Determine-which-child-table-a-record-belongs-to-tp15164998p15165402.html > Sent from the Apache Derby Users mailing list archive at Nabble.com. >