Hi,

I would like to implement a trigger on my tables. My structure is simple. You have a leaf and Branch:

-Table Leafs
id (PK)
branchid (FK)

============

-Table Branch
id (PK)
leafcount (needs to be triggered)


Simple, a branch has many leafs. But when I insert a new leaf, I need the Branch(leafcount) to increment.

Any ideas?

You will need 3 triggers, one during insert to increment the leafcount, one during insert to decrement the leaf count and one during the update to verify that the branch is not changing from one to another in which case you will need to decrement one and increment another leafcount. To verify the update use the old.branchid and new.branchid while determining what to do. Of course if they are the same then no new calculation is required.