Relationships and Include related values - I'm lost
I've looked and looked, but I now admit defeat! I need help!
I come from a bit of a SQL background so I thought I knew what I was doing, but apparently not. I now half suspect my ER style thinking is actually a getting in the way of understanding how the relationship graph works.
Anyway, imagine you have the tables RemoteInventory, BatteryInventory, BatteryMakes, RemoteMakes, BatteryType.
BatteryMakes, and RemoteMakes both have a BatteryType, and RemotesInventory has a CurrentBatteryInventory item (only of its RmoteMakes BatteryType), and BatteryInventory has a InstalledInRemoteInventory item (only of its BatteryMakes BatteryType).
Do you get what happens? For any RemoteInventory item you can see \ change the battery that is currently installed, but only of the shared BatteryType (thus only one battery can ever be installed in a item), and conversely through BatteryInventory you can see how many batteries have been installed for any one RemoteInventory.
Anyway, I have no idea how to limit the values from to those of its BatteryType and could really use some help or some pointers. I know it has something to do with the relationship graph, but I feel more clueless now that I did before!