Only show action button if an query returns false

magluca

Hey,
In my dataTables i have an action button in the last column, but i only want to show this button if a query i send to my database is false (if the data in the row is not registered in another db)
In the live datatable below you can see how i structure my table (even though my ajax call doesnt work - but you get the point):
http://live.datatables.net/talufopo/1/edit?html,js,output

I have set the defaultContent on my last column, creating a link/button, but how can i first send a query to my database/run a function, to check if i want to display the defaultContent?