[HACKERS] PQntuples and PQgetvalue problem.

[zafer yagmuroglu]

Hello,

In my C++ program, i want to partition sql table, there is sample code below. 
It is working right. the problem is after func  called 2 or 3 times in func1, 
PQntuples results 0 although tablename exist.  Also when i disabled PQntuples 
at if statement, other psql function PQgetvalue(res) return error that is "row 
number 0 is out of range 0..-1there are a couple function call same as func1(to 
check tablename ), at func. when i disabled one of them another at PQntuples 
funcx return 0.  i check so may times. it is so weird.
So i think you can help me.
Best regards.
Zafer,

Sample code : 

func1{
      char cmd[100] = "";
      snprintf(cmd,sizeof(cmd),"select tablename from pg_tables where 
tablename='%s'",  tablename);

      PGresult *res = PQexec(conn, cmd );

      if (PQresultStatus(res) != PGRES_TUPLES_OK)
       {
             logger.error("PQexec: %s", PQerrorMessage(conn));
             PQclear(res);
             wexit(1);
       }

      if (PQntuples(res) == 0)
        //
      } 

      func {
      PGresult *res;
      func1();
      res=PQexec(conn,"Select count(*) from persons");
      if (PQresultStatus(res) != PGRES_TUPLES_OK)
      {
      printf("PQexec: %s", PQerrorMessage(conn));
      PQclear(res);
      exit(1);
      }
      if( atoi(PQgetvalue(res,0,0)) != 0)
        // some code PQexec()}    }