Обсуждение: Return PGresult

Hi,
PGresult is a structure.
I want to return PGresult pointer.(Code is given below.)
Is this possible ? if yes , please give me the solution.
Thanks in Advance.
Anuj
===========================
/* tempdb=>create table tbltemp (id int4, name varchar(30)); */
#include <stdio.h>
#include <pgsql/libpq-fe.h>

main()
{
    int totalrec;
    PGresult *resu;
    dbQuery("tempdb","select * from tbltemp",&totalrec,resu);
    printf("\n The total rec  = %i\n", totalrec);
    printf(" The total rec  = %i\n",  PQntuples(resu));
} /* End of main */

 dbQuery(char * dbName, char *sqlstatement , int *totalrec,PGresult *res)
 {
      PGconn     *conn;
      char fullsql[500];
      conn = PQsetdb(NULL, NULL, NULL, NULL, dbName);
      res = PQexec(conn, "BEGIN");
      PQclear(res);
      strcpy(fullsql , "DECLARE mycursor CURSOR FOR ");
      strcat(fullsql,sqlstatement);
      res = PQexec(conn, fullsql);
      PQclear(res);
      res = PQexec(conn, "FETCH ALL in mycursor");
      *totalrec = PQntuples(res);
 }
===========================

Out put :
$
The total rec  = 2 // This result is right.
The total rec  = 0 // The same result is not showing.
$

anuj wrote:
>
> Hi,
> PGresult is a structure.
> I want to return PGresult pointer.(Code is given below.)
> Is this possible ? if yes , please give me the solution.
> Thanks in Advance.
> Anuj
> ===========================
> /* tempdb=>create table tbltemp (id int4, name varchar(30)); */
> #include <stdio.h>
> #include <pgsql/libpq-fe.h>
>
> main()
> {
>     int totalrec;
>     PGresult *resu;
>     dbQuery("tempdb","select * from tbltemp",&totalrec,resu);
>     printf("\n The total rec  = %i\n", totalrec);
>     printf(" The total rec  = %i\n",  PQntuples(resu));
> } /* End of main */
>
>  dbQuery(char * dbName, char *sqlstatement , int *totalrec,PGresult *res)
>  {
>       PGconn     *conn;
>       char fullsql[500];
>       conn = PQsetdb(NULL, NULL, NULL, NULL, dbName);
>       res = PQexec(conn, "BEGIN");
>       PQclear(res);
>       strcpy(fullsql , "DECLARE mycursor CURSOR FOR ");
>       strcat(fullsql,sqlstatement);
>       res = PQexec(conn, fullsql);
>       PQclear(res);
>       res = PQexec(conn, "FETCH ALL in mycursor");
>       *totalrec = PQntuples(res);
>  }
> ===========================
>
> Out put :
> $
> The total rec  = 2 // This result is right.
> The total rec  = 0 // The same result is not showing.
> $

Try
dbQuery("tempdb","select * from tbltemp",&totalrec,&resu);
and the function declaration
dbQuery(char *dbName,char *sqlststatement,int *totalrec,PGresult **res);
and then within the function reference it as *res=




--
Dave Smith
Candata Systems Ltd.
(416) 493-9020
dave@candata.com

Thanks,I'm trying PGresult pointer to pointer.
And Why don't PGresult pointer variable reqiure memory allocation (malloc()?
Like /* resu =  (PGresult *)(malloc(sizeof(PGresult)); */

-----Original Message-----
From: dave@playpen.candata.com [mailto:dave@playpen.candata.com]On
Behalf Of Dave Smith
Sent: Thursday, July 20, 2000 5:21 PM
To: anuj
Cc: pgsql-general@postgresql.org
Subject: Re: [GENERAL] Return PGresult


anuj wrote:
>
> Hi,
> PGresult is a structure.
> I want to return PGresult pointer.(Code is given below.)
> Is this possible ? if yes , please give me the solution.
> Thanks in Advance.
> Anuj
> ===========================
> /* tempdb=>create table tbltemp (id int4, name varchar(30)); */
> #include <stdio.h>
> #include <pgsql/libpq-fe.h>
>
> main()
> {
>     int totalrec;
>     PGresult *resu;
>     dbQuery("tempdb","select * from tbltemp",&totalrec,resu);
>     printf("\n The total rec  = %i\n", totalrec);
>     printf(" The total rec  = %i\n",  PQntuples(resu));
> } /* End of main */
>
>  dbQuery(char * dbName, char *sqlstatement , int *totalrec,PGresult *res)
>  {
>       PGconn     *conn;
>       char fullsql[500];
>       conn = PQsetdb(NULL, NULL, NULL, NULL, dbName);
>       res = PQexec(conn, "BEGIN");
>       PQclear(res);
>       strcpy(fullsql , "DECLARE mycursor CURSOR FOR ");
>       strcat(fullsql,sqlstatement);
>       res = PQexec(conn, fullsql);
>       PQclear(res);
>       res = PQexec(conn, "FETCH ALL in mycursor");
>       *totalrec = PQntuples(res);
>  }
> ===========================
>
> Out put :
> $
> The total rec  = 2 // This result is right.
> The total rec  = 0 // The same result is not showing.
> $

Try
dbQuery("tempdb","select * from tbltemp",&totalrec,&resu);
and the function declaration
dbQuery(char *dbName,char *sqlststatement,int *totalrec,PGresult **res);
and then within the function reference it as *res=




--
Dave Smith
Candata Systems Ltd.
(416) 493-9020
dave@candata.com

anuj wrote:
>
> Thanks,I'm trying PGresult pointer to pointer.
> And Why don't PGresult pointer variable reqiure memory allocation (malloc()?
> Like /* resu =  (PGresult *)(malloc(sizeof(PGresult)); */
>
I believe that the  PQexec is doing the allocation. That is why it has
to be pointer to pointer.

--
Dave Smith
Candata Systems Ltd.
(416) 493-9020
dave@candata.com

Thanks,
Now, I am able to return PGresult. Pointer to pointer is working fine.
And about memory allocation. Before the PQexec we can't decide required
memory. So, PQexec doing the memory allocation.
Cherries
Anuj
>Try
>dbQuery("tempdb","select * from tbltemp",&totalrec,&resu);
>and the function declaration
>dbQuery(char *dbName,char *sqlststatement,int *totalrec,PGresult **res);
>and then within the function reference it as *res=

-----Original Message-----
From: pgsql-general-owner@hub.org [mailto:pgsql-general-owner@hub.org]On
Behalf Of Dave Smith
Sent: Thursday, July 20, 2000 5:46 PM
To: anuj
Cc: pgsql-general@postgresql.org
Subject: Re: [GENERAL] Return PGresult


anuj wrote:
>
> Thanks,I'm trying PGresult pointer to pointer.
> And Why don't PGresult pointer variable reqiure memory allocation
(malloc()?
> Like /* resu =  (PGresult *)(malloc(sizeof(PGresult)); */
>
I believe that the  PQexec is doing the allocation. That is why it has
to be pointer to pointer.

--
Dave Smith
Candata Systems Ltd.
(416) 493-9020
dave@candata.com