Cascading drop down default value

I have cascading dropdowns that pulls data from tables and is working well but I wish to enhance it. The first dd lists databases and the second dd lists the schema and the last one lists the tables. The schema dropdown pulls records from a schema table that looks something like this:

sID  Name  DbID

1     dbo        10

2     dbo        20

3    dev          10

4    dbo         30

5    smpl        20

6     bkup       30

The enhancement i wish to have is when a user selects any database, the schema dropdown will have the 'dbo' as the default selected value.

Thanks for the time and effort of helping me.