About DBD Prepare Statement Problem

[liuxulin]

hi everybody,

I've got some problems, hope for your helps.
 1.
 When i try to connect Mysql with 'apr-util DBD' , But get some errors.
 After executing 'apr_dbd_pvselect', I got the result 'empty value'.
 But i can get correct result with the 'apr_dbd_select' method.

 in my code:
 entry = apr_dbd_get_entry(driver, row, n);
   but I got nothing.

 How to fix the 'empty value' problem?

 2.
 I try to query "select * from ..." but got a "Exec of prepared 
statement failed!"
 But "select userName from ..." makes the right results.

 Is there anything wrong?


Thanks for your helps and replies!

My code is as follows:

Environment:
 apr-util : 1.3.9
 ubuntu   : 9.04
 mysql    : 5.0.75
 TABLE  Structure:
 CREATE TABLE `testTable` {
  `id` int(11) NOT NULL,
  `userName` varchar(100) NOT NULL,
  PRIMARY KEY (`id`)
 }ENGINE=MyISAM DEFAULT CHARSET=latin1;
    Source：
#include "apu.h"
#include "apr_pools.h"
#include "apr_dbd.h"

#include <stdio.h>

int main(int argc, char **argv) {
  const char *name = "mysql";
  const char *params =
          "host=127.0.0.1,user=root,pass=123456,dbname=testDB,port=3306";
  apr_pool_t *pool = NULL;
  apr_dbd_t *sql = NULL;
  const apr_dbd_driver_t *driver = NULL;
  int rv;

  const char *query = "SELECT  userName  FROM testTable where 
id=%d";/*this query exec info:ok!!!*/
  //const char *query = "SELECT * FROM testTable where id=%d";/*this 
query exec info:"Exec of prepared statement failed!"???*/
  const char *label = "getUserName";
  apr_dbd_prepared_t *statement = NULL;
  apr_dbd_results_t *res = NULL;
  apr_dbd_row_t *row = NULL;
  const char *entry = NULL;
  int i, n;

  apr_initialize();
  apr_pool_create(&pool, NULL);

  apr_dbd_init(pool);
  rv = apr_dbd_get_driver(pool, name, &driver);

  switch (rv) {
  case APR_SUCCESS:
      printf("Loaded %s driver OK.\n", name);
      break;
  case APR_EDSOOPEN:
      printf("Failed to load driver file apr_dbd_%s.so\n", name);
      goto finish;
  case APR_ESYMNOTFOUND:
      printf("Failed to load driver apr_dbd_%s_driver.\n", name);
      goto finish;
  case APR_ENOTIMPL:
      printf("No driver available for %s.\n", name);
      goto finish;
  default: /* it's a bug if none of the above happen */
      printf("Internal error loading %s.\n", name);
      goto finish;
  }

  rv = apr_dbd_open(driver, pool, params, &sql);
  switch (rv) {
  case APR_SUCCESS:
      printf("Opened %s[%s] OK\n", name, params);
      break;
  case APR_EGENERAL:
      printf("Failed to open %s[%s]\n", name, params);
      goto finish;
  default: /* it's a bug if none of the above happen */
      printf("Internal error opening %s[%s]\n", name, params);
      goto finish;
  }

  rv = apr_dbd_prepare(driver, pool, sql, query, label, &statement);
  if (rv) {
      printf("Prepare statement failed!\n%s\n",
              apr_dbd_error(driver, sql, rv));
      return rv;
  }

  int user_id = 1;
  rv
          = apr_dbd_pvselect(driver, pool, sql, &res, statement, 0, 
&user_id,
                  NULL);

  if (rv) {
      printf("Exec of prepared statement failed!\n%s\n", apr_dbd_error(
              driver, sql, rv));
      return rv;
  }

  i = 0;
  for (rv = apr_dbd_get_row(driver, pool, res, &row, -1); rv == 0; rv
          = apr_dbd_get_row(driver, pool, res, &row, -1)) {
      printf("ROW %d:    ", ++i);
      for (n = 0; n < apr_dbd_num_cols(driver, res); ++n) {
          entry = apr_dbd_get_entry(driver, row, n);
          if (entry == NULL) {
              printf("(null)    ");
          } else {
              printf("%s    ", entry);/*printf Nothing???*/
          }
      }
      fputs("\n", stdout);
  }

  finish:
      printf("finish");
      apr_pool_destroy(pool);
      apr_terminate();              
      return 0;
}