Err: MySQL_CONNECTION::setReadOnly() in C++ application

[Winston Lim]

Hi, I'm new to Mysql. I tried to compile and run the example source code from Mysql website. The code is listed below:

#include "mysql_connection.h"
#include <cppconn/driver.h>
#include <cppconn/exception.h>
#include <cppconn/resultset.h>
#include <cppconn/statement.h>
using namespace std;

#define EXAMPLE_HOST "localhost"
#define EXAMPLE_USER "root"
#define EXAMPLE_PASS "get your own password here"
#define EXAMPLE_DB "information_schema"

int main(int argc, const char **argv)
{
const string url(argc >= 2 ? argv[1] : EXAMPLE_HOST);
const string user(argc >= 3 ? argv[2] : EXAMPLE_USER);
const string pass(argc >= 4 ? argv[3] : EXAMPLE_PASS);
const string database(argc >= 5 ? argv[4] : EXAMPLE_DB);

try {
sql::Driver *driver;
sql::Connection *con;
sql::Statement *stmt;
sql::ResultSet *res;

driver = get_driver_instance(); /* Create a connection */
con = driver->connect("tcp://" + url + ":3306", user, pass);
con->setSchema(database); /* Set the database */

stmt = con->createStatement();
res = stmt->executeQuery("SELECT 'Hello World!' AS _message");

while (res->next())
{
cout << "\t... MySQL replies: ";
cout << res->getString("_message") << endl;
cout << "\t... MySQL says it again: ";
cout << res->getString(1) << endl;
}
delete res;
delete stmt;
delete con;
} catch (sql::SQLException &e) {
/*
The MySQL Connector/C++ throws three different exceptions:

- sql::MethodNotImplementedException (derived from sql::SQLException)
- sql::InvalidArgumentException (derived from sql::SQLException)
- sql::SQLException (derived from std::runtime_error)
*/
cout << "# ERR: SQLException in " << __FILE__;
cout << "(" << __FUNCTION__ << ") on line " << __LINE__ << endl;
/* Use what() (derived from std::runtime_error) to fetch the error message */
cout << "# ERR: " << e.what();
cout << " (MySQL error code: " << e.getErrorCode();
cout << ", SQLState: " << e.getSQLState() << " )" << endl;

return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}

The program compile and run correctly if I remove the line:
con->setSchema(database); /* Set the database */
It doesn't work if I run the application with the line above, with the error:
ERR: MySQL_Connection::setREADONLY()

May I know why?