>1. Get rid of the empty record
>
>2. What do you use to provide this field uniqueness? NextID() idea?
>This is a table for horses and the uniqueness field idea is because a horse can only have one parent.
>
>BTW, why do you need Numeric 10? Will Integer work for you?
>because i need to related with the others tables with the same type of field.

Change it, in both places. Integer data type requires 4 bites, N(10) - 10 bites. Of course in Integer you could store values from -2147483647 to 2147483647 but I think this is enough.