C++ insert data to MySQL return error

Question

I modified a set of code from MySQL page to test input data into MySQL table 'list'. The program exits with the following error

terminate called after throwing an instance of 'sql::SQLException'
  what():  
Aborted

After I checked through the table, the data was successfully inserted somehow. I modified this program to repeat inserting the data using a for loop but end up the loop exited after first iteration (program forced to exit during first insertion).

I also tried with hard-coded query, which worked in MySQL manually input, but still had the same issue.

#include <stdlib.h>
#include <iostream>
#include <string>
#include "mysql_connection.h"
#include <cppconn/driver.h>
#include <cppconn/exception.h>
#include <cppconn/resultset.h>
#include <cppconn/statement.h>
#include <mysql_driver.h>

using namespace std;

int main(void){
        cout << endl;
        cout << "Running test insert"  << endl;

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

        /* Create a connection */
        driver = get_driver_instance();
        con = driver->connect("localhost", "dev", "1234");

        /* Connect to the MySQL test database */
        con->setSchema("million");

        string data("abc1234567890");

        stmt = con->createStatement();
        res = stmt->executeQuery("INSERT INTO list VALUES('0','" +
            data + "','" + data +"','" + data + "','" + data + "','" +     data + "');");
        }
        // replace with your statement
        delete res;
        delete stmt;
        delete con;

        cout << endl;

        return EXIT_SUCCESS;

}

With this try{} catch

try{....}
catch (sql::SQLException &e) {
    cout << "# ERR: SQLException in " << __FILE__;
    cout << "(" << __FUNCTION__ << ") on line " << __LINE__ << endl;     
    cout << "# ERR: " << e.what();
    cout << " (MySQL error code: " << e.getErrorCode();
    cout << ", SQLState: " << e.getSQLState() << " )" << endl;}

Output this error message

# ERR: SQLException in test.cpp(main) on line 54
# ERR:  (MySQL error code: 0, SQLState: 00000 )

WARNING: Do not forget to properly escape your values. What you've got here is one step away from a severe SQL injection bug. Be sure to use prepared statements when adding data to your queries. — tadman
– tadman, Commented Mar 3, 2015 at 15:35
I recommend formatting your SQL query into a string before placing into the function. This will allow you to use a debugger and examine the contents of the string before it is sent to the MySQL database. — Thomas Matthews
– Thomas Matthews, Commented Mar 3, 2015 at 16:58

Nikola Obreshkov · Accepted Answer · 2018-09-09 14:09:38Z

2

The sql::SQLException is thrown because the executeQuery() function is supposed to return a sql::ResultSet after the SQL query execution (e.g. SELECT statement). For SQL queries that does not return any DB selection (e.g. CREATE, UPDATE) there is another function execute().

The original answer can be found here: MySQL Query executes but throws exception

answered Sep 9, 2018 at 14:09

Nikola Obreshkov

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Comments

jgnoss · Accepted Answer · 2016-04-21 13:05:18Z

0

I had the same problem and come across this post. So just for the records. I did an

if (res) {
  doSomeThing();
}

after executing the statement and the SQLException disappeared

answered Apr 21, 2016 at 13:05

jgnoss

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