Get a LIBPQ document from the second drawer of the file cabinet.
The online document is in the directory ~picasso/doc/libpq.

To use libpq, follow these steps:
1) (use-package 'libpq)
2) (pqsetdb "ywang")  	where "ywang" can be other DB names
3) (pqexec "retrieve (x = 1)") 	where query is a POSTGRES query
4) goto step 5)

in case there is an error:
:pop
(pqreset)

When you quit:
(pqfinish)

A typical portal query should be something like this:

(pqexec "retrieve portal foo (emp.all)")
(pqexec "fetch all in foo")
(setq foo (pqparray "foo"))
(setq n (pqntuples foo))

