Help with asynchronous queries

Hi, I need to execute some queries that do not return any value
for example "DELETE * FROM foo". This queries take a lot of time and I 
can't put them together in a single query.
If I use the non-blocking function PQsendQuery() I have to wait until 
the execution of the first query terminates before executing another 
query right?
In my case (without a result for the query) is it right to check only if 
PQisBusy returns 0 inside a loop before executing the next query?
Or do I have to check the connection socket with a select and then do a 
PGconsumeInput when data is avaible and at the end check PQisBusy?