update query with list box

[indeed_2000]

Hi

I create simple dropdown list on dashboard.

Now I want to modify query with this dropdown list 

e.g.

my dropdown list: APP1, APP2, APP3,...

my query: index="myindex" source="/data/APP1"

when I select APP2 query change to this  index="myindex" source="/data/APP2"

FYI: I don't want to use field or any think else just directly modify query

Any Idea?

Thanks,