MySql C++连接器getString()无法正常工作,而getInt工作正常

Question

我试图将C++连接到MySql,但我无法让它正常工作.我从Oracle站点使用了最新的MySql和C++/Connector for Windows.我也用VS2010.

它编译,一切都工作除了getString!我使用了他们提供的一些调整示例:

#include "stdafx.h"


#include <stdlib.h>
#include <iostream>
#include <sstream>
#include <stdexcept>

#include <driver/mysql_public_iface.h>

#include "examples.h"

using namespace std;

int main(int argc, const char **argv)
{
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);

/* sql::ResultSet.rowsCount() returns size_t */
size_t row;
stringstream sql;
stringstream msg;
int i, affected_rows;

cout << boolalpha;
cout << "1..1" << endl;
cout << "# Connector/C++ connect basic usage example.." << endl;
cout << "#" << endl;

try {
    sql::Driver * driver = sql::mysql::get_driver_instance();
    /* Using the Driver to create a connection */
    std::auto_ptr< sql::Connection > con(driver->connect("localhost", "root", "root"));

    /* Creating a "simple" statement - "simple" = not a prepared statement */
    std::auto_ptr< sql::Statement > stmt(con->createStatement());

    /* Create a test table demonstrating the use of sql::Statement.execute() */
    stmt->execute("USE publications");
    cout << "#\t Test table created" << endl;

    /* Populate the test table with data */

    cout << "#\t Test table populated" << endl;

    {
        /*
        Run a query which returns exactly one result set like SELECT
        Stored procedures (CALL) may return more than one result set
        */
        std::auto_ptr< sql::ResultSet > res(stmt->executeQuery("SELECT id, task FROM to_do_list ORDER BY id ASC"));
        cout << "#\t Running 'SELECT id, task FROM to_do_list ORDER BY id ASC'" << endl;

        /* Number of rows in the result set */
        cout << "#\t\t Number of rows\t";
        cout << "res->rowsCount() = " << res->rowsCount() << endl;
        if (res->rowsCount() != EXAMPLE_NUM_TEST_ROWS) {
            msg.str("");
            msg << "Expecting " << EXAMPLE_NUM_TEST_ROWS << "rows, found " << res->rowsCount();
            throw runtime_error(msg.str());
        }

        /* Fetching data */
        row = 0;
        while (res->next()) {
            cout << "#\t\t Fetching row " << row << "\t";
            /* You can use either numeric offsets... */
            cout << "id = " << res->getInt("id");
            /* ... or column names for accessing results. The latter is recommended. */
            cout << ", task = '" << res->getString("task") << "'" << endl;
            row++;
            system("PAUSE");
        }
    }

...... //其余部分不相关,因为它在这里打破了.

这是输出:

1..1
# Connector/C++ connect basic usage example..
#
#        Test table created
#        Test table populated
#        Running 'SELECT id, task FROM to_do_list ORDER BY id ASC'
#                Number of rows res->rowsCount() = 4
#                Fetching row 0 id = 3, task = ''
Press any key to continue . . .
#                Fetching row 1 id = 7, task = ''
Press any key to continue . . .
   ?   Ñ?½x R=  I>             ?   £I> task  ? 4å@ xQ@ ?   ?   ?    ocalhost ½xÇ
'
Press any key to continue . . .

这就是桌子看起来很清楚它没有正常工作.我只是无法从MySql获取varchar(120)的字符串:

mysql> use publications
Database changed
mysql> select id, task from to_do_list;
+----+---------------------------+
| id | task                      |
+----+---------------------------+
|  9 | prepare for calculus      |
|  3 | buy jeans                 |
|  8 | buy new scale             |
|  7 | buy Ethics book for class |
+----+---------------------------+
4 rows in set (0.00 sec)

我试过VS2008,这就是我得到的:

msvcp90d.dll!104e8dcb()
[下面的框架可能不正确和/或缺失,没有为msvcp90d.dll加载符号]
try_mysql_native.exe!std :: operator <<(std :: basic_ostream>&os = {...} ,const sql :: SQLString&str = {...})第196行+ 0x1f字节C++ try_mysql_native.exe!main(int argc = 1,const char**argv = 0x003e63e8)第115行+ 0xa5字节C++ try_mysql_native.exe! __tmainCRTStartup()第586行+ 0x19字节C try_mysql_native.exe!mainCRTStartup()第403行C kernel32.dll!7c817077()

还有这个:

'try_mysql_native.exe':已加载'C:\ Documents and Settings\Eugene\My Documents\Visual Studio 2008\Projects\try_mysql_native\Debug\try_mysql_native.exe',已加载符号.'try_mysql_native.exe':已加载'C:\ WINDOWS\system32 \ntdll.dll''try_mysql_native.exe':已加载'C:\ WINDOWS\system32\kernel32.dll''try_mysql_native.exe':已加载'C:\ WINDOWS\system32\mysqlcppconn.dll''try_mysql_native.exe':已加载'C:\ WINDOWS\system32\libmysql.dll',已加载符号.'try_mysql_native.exe':已加载'C:\ WINDOWS\system32\advapi32.dll''try_mysql_native.exe':已加载'C:\ WINDOWS\system32\rpcrt4.dll''try_mysql_native.exe':已加载'C:\ WINDOWS\system32\secur32.dll''try_mysql_native.exe':已加载'C:\ WINDOWS\system32\ws2_32.dll''try_mysql_native.exe':已加载'C:\ WINDOWS\system32\msvcrt.dll''try_mysql_native.exe' :已加载'C:\ WINDOWS\system32\ws2help.dll''try_mysql_native.exe':已加载'C:\ WINDOWS\WinSxS\x86_Microsoft.VC90.CRT_1fc8b3b9a1e18e3b_9.0.30729.4974_x-ww_d889290f\msvcp90.dll''try_mysql_native.exe' :已加载'C:\ WINDOWS\WinSxS\x86_Microsoft.VC90.CRT_1fc8b3b9a1e18e3b_9.0.30729.4974_x-ww_d889290f\msvcr90.dll''try_mysql_native.exe':已加载'C:\ WINDOWS\WinSxS\x86_Microsoft.VC90.DebugCRT_1fc8b3b9a1e18e3b_9.0.30729.1_x -ww_f863c71f\msvcr90d.dll''try_mysql_native.exe':已加载'C:\ WINDOWS\WinSxS\x86_Microsoft.VC90.DebugCRT_1fc8b3b9a1e18e3b_9.0.30729.1_x-ww_f863c71f\msvcp90d.dll''try_mysql_native.exe':已加载'C:\ WINDOWS\system32\mswsock.dll''try_mysql_na tive.exe':已加载'C:\ WINDOWS\system32\dnsapi.dll''try_mysql_native.exe':已加载'C:\ WINDOWS\system32\winrnr.dll''try_mysql_native.exe':已加载'C:\ WINDOWS\system32\wldap32.dll''try_mysql_native.exe':已加载'C:\ Program Files\Bonjour\mdnsNSP.dll''try_mysql_native.exe':已加载'C:\ WINDOWS\system32\iphlpapi.dll''try_mysql_native.exe' :加载'C:\ WINDOWS\system32\user32.dll''try_mysql_native.exe':加载'C:\ WINDOWS\system32\gdi32.dll''try_mysql_native.exe':加载'C:\ WINDOWS\system32\imm32. dll''try_mysql_native.exe':已加载'C:\ WINDOWS\system32\rasadhlp.dll''try_mysql_native.exe':已加载'C:\ WINDOWS\system32\hnetcfg.dll''try_mysql_native.exe':已加载'C:\WINDOWS\system32\wshtcpip.dll在try_mysql_native.exe中的0x104e8dcb处的第一次机会异常:0xC0000005:访问冲突读取位置0x6e61656a.try_mysql_native.exe中0x104e8dcb处的未处理异常:0xC0000005:访问冲突读取位置0x6e61656a.try_mysql_native.exe中0x104e8dcb的第一次机会异常:0xC0000005:访问冲突读取位置0x6e61656a.try_mysql_native.exe中0x104e8dcb处的未处理异常:0xC0000005:访问冲突读取位置0x6e61656a.try_mysql_native.exe中0x104e8dcb的第一次机会异常:0xC0000005:访问冲突读取位置0x6e61656a.try_mysql_native.exe中0x104e8dcb处的未处理异常:0xC0000005:访问冲突读取位置0x6e61656a.try_mysql_native.exe中0x104e8dcb的第一次机会异常:0xC0000005:访问冲突读取位置0x6e61656a.try_mysql_native.exe中0x104e8dcb处的未处理异常:0xC0000005:访问冲突读取位置0x6e61656a.try_mysql_native.exe中0x104e8dcb的第一次机会异常:0xC0000005:访问冲突读取位置0x6e61656a.try_mysql_native.exe中0x104e8dcb处的未处理异常:0xC0000005:访问冲突读取位置0x6e61656a.try_mysql_native.exe中0x104e8dcb的第一次机会异常:0xC0000005:访问冲突读取位置0x6e61656a.try_mysql_native.exe中0x104e8dcb处的未处理异常:0xC0000005:访问冲突读取位置0x6e61656a.try_mysql_native.exe中0x104e8dcb的第一次机会异常:0xC0000005:访问冲突读取位置0x6e61656a.try_mysql_native.exe中0x104e8dcb处的未处理异常:0xC0000005:访问冲突读取位置0x6e61656a.try_mysql_native.exe中0x104e8dcb的第一次机会异常:0xC0000005:访问冲突读取位置0x6e61656a.try_mysql_native.exe中0x104e8dcb处的未处理异常:0xC0000005:访问冲突读取位置0x6e61656a.

Answer 1

我有一个类似的问题,该程序将给出一个内存异常.这是我做的修复它:

std::string version = result->getString( COLUMN_NAME ).c_str();

这不起作用:

sql::SQLString sString  = result->getString( COLUMN_NAME ); <<<memory exception
std::string version = sString;