asynchronour queries and result testing

Hello,

I have this query in my .c program:

    if (PQsendQuery(srcmain, "select
userid,uid,clear_passwd,www_home,date_part('epoch',dt_block),date_part('epoch',dt_cancel)from www where uid=parent_uid
anddt_modify > dt_export")) { 
        while ((srcmres = PQgetResult(srcmain)) != NULL) {

well as doc says,
    "Each non-null result from PQgetResult should be processed using the
    same PGresult accessor functions previously described."

do i understand it correctly?

            /* process each returned line */
            if ((srcmstat = PQresultStatus(srcmres)) != PGRES_TUPLES_OK)
                fprintf(stderr, "error getting result: %s\n",
                    PQresultErrorMessage(srcmres));
            else {
                if ((srcmtup = PQntuples(srcmres)) == 6) {

I just would like to know, if, in case of problem couldn't just return NULL
and fill out error message; could I just process the result and if there's
no data (or an error), NULL would be returned and PQresStatus could be
called to see if any problem occured.

Anyway, even if I get resule with 0 tuples, I need to check PQntuples and it
returns 0.
i think checking PQntuples in big loop is quite unefficient.

could anybody comment this?

Thanks.

--
 Matus "fantomas" Uhlar, sysadmin at NEXTRA, Slovakia; IRCNET admin of *.sk
 uhlar@fantomas.sk ; http://www.fantomas.sk/ ; http://www.nextra.sk/
 WinError #99999: Out of error messages.