MySql C ++连接器getString（）不能正常工作，而getInt工作完美 [英] MySql C++ connector getString() doesn't work correctly, while getInt works perfectly

问题描述

我试图连接C ++到MySql，我只是不能让这个工作正常。我从Oracle网站使用了最新的MySql和C ++ / Connector for Windows。我也使用VS2010。

它编译和一切工作除了getString！我用他们提供一些调整的例子：

  #includestdafx.h
 
 
 #include< stdlib.h> 
 #include< iostream> 
 #include< sstream> 
 #include< stdexcept> 
 
 #include< driver / mysql_public_iface.h> 
 
 #includeexamples.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（）返回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（）; 
 / *使用驱动程序创建连接* / 
 std :: auto_ptr< sql :: Connection> con（driver-> connect（localhost，root，root））; 
 
 / *创建一个简单语句 - simple=不是准备语句* / 
 std :: auto_ptr< sql :: Statement> stmt（con> createStatement（））; 
 
 / *创建一个测试表，演示如何使用sql :: Statement.execute（）* / 
 stmt-> execute（USE publications）; 
 cout<< ＃\t Test table created<< endl; 
 
 / *用数据填充测试表* / 
 
 cout<< ＃\t Test table populated< endl; 
 
 {
 / * 
运行查询，返回正好一个结果集，如SELECT 
存储过程（CALL）可能返回多个结果集
 * / 
 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; 
 
 / *结果集中的行数* / 
 cout<< ＃\t\t Number of rows \t; 
 cout<< res-> rowsCount（）=<< res-> rowsCount（）<< endl; 
 if（res-> rowsCount（）！= EXAMPLE_NUM_TEST_ROWS）{
 msg.str（）; 
 msg<< 期望< EXAMPLE_NUM_TEST_ROWS<< rows，found< res-> rowsCount（）; 
 throw runtime_error（msg.str（））; 
} 
 
 / *获取数据* / 
 row = 0; 
 while（res-> next（））{
 cout< ＃\t\t Fetching row<<行<< \t; 
 / *你可以使用数字偏移... * / 
 cout<< id =< res-> getInt（id）; 
 / * ...或用于访问结果的列名称。建议使用后者。 * / 
 cout<< ，task ='<< res-> getString（task）<< '< endl; 
 row ++; 
 system（PAUSE）; 
} 
} 
  

... //因为它打破了这里。

这是输出：

  1 。
＃连接器/ C ++连接的基本用法示例.. 
＃
＃创建测试表
＃填充测试表
＃运行'SELECT id，task FROM to_do_list ORDER BY id ASC'
＃行数res-> rowsCount（）= 4 
＃获取行0 id = 3，任务=''
按任意键继续。 。 。 
＃获取行1 id = 7，任务=''
按任意键继续。 。 。 
☼Ñ╤½xR = I> ☼I>任务↕4å@ xQ @☼☻ocalhost½xÇ
'
按任意键继续。 。 。 
  

这是桌子看起来像这样清楚它不能正常工作。我只是不能得到它的字符串varchar（120）从MySql：

  mysql>使用出版物
数据库已更改
 mysql>选择id，任务从to_do_list; 
 + ---- + --------------------------- + 
 | id |任务| 
 + ---- + --------------------------- + 
 | 9 |准备微积分| 
 | 3 |买牛仔裤| 
 | 8 |购买新规模| 
 | 7 |购买类的伦理书| 
 + ---- + --------------------------- + 
集合中的4行（0.00秒） 
 

我试过VS2008，这是我得到的：

msvcp90d.dll！104e8dcb（）

[下面的框可能不正确和/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 = {...}）196 + 0x1f字节C ++
try_mysql_native.exe！主（INT ARGC = 1，为const char * argv的= 0x003e63e8）线115 +的0xA5字节C ++
try_mysql_native.exe！__ tmainCRTStartup（）行586 +的0x19字节ç
try_mysql_native .exe！mainCRTStartup（）Line 403 C
kernel32.dll！7c817077（）





try_mysql_native.exe：已加载C：\Documents和Settings\Eugene\My Documents\Visual工作室2008\Projects\try_mysql_native\Debug\try_mysql_native .exe'，加载符号。
'try_mysql_native.exe'：加载'C：\WINDOWS\system32\\\\\\'dll.dll'
'try_mysql_native.exe'：加载'C：\WINDOWS\system32\kernel32。 dll'
'try_mysql_native.exe'：Loaded'C：\WINDOWS\system32\mysqlcppconn.dll'
'try_mysql_native.exe'：Loaded'C：\WINDOWS\system32 \ libmysql.dll'，加载符号。
'try_mysql_native.exe'：加载'C：\WINDOWS\system32\advapi32.dll'
'try_mysql_native.exe'：加载'C：\WINDOWS\system32\rpcrt4。 dll'
'try_mysql_native.exe'：加载'C：\WINDOWS\system32\secur32.dll'
'try_mysql_native.exe'：加载'C：\WINDOWS\system32 \ ws2_32.dll'
'try_mysql_native.exe'：加载'C：\WINDOWS\system32 \ msvcrt.dll'
'try_mysql_native.exe'：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'：加载'C：\WINDOWS\system32\mswsock.dll'
'try_mysql_native.exe'：Loaded' C：\WINDOWS\system32\dnsapi.dll'
'try_mysql_native.exe'：加载'C：\WINDOWS\system32\winrnr.dll'
'try_mysql_native.exe'：加载C：\WINDOWS\system32\wldap32.dll'
'try_mysql_native.exe：已加载C：\Program Files\Bonjour\mdnsNSP.dll'
'try_mysql_native。 exe'：Loaded'C：\WINDOWS\ system32 \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\''''
'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'：加载'C：\WINDOWS\system32\rasadhlp.dll'
'try_mysql_native.exe'：加载'C：\WINDOWS\system32\hnetcfg.dll'
'try_mysql_native.exe：已加载C：\WINDOWS\system32\wshtcpip.dll'
第一次机会异常在0x104e8dcb在try_mysql_native.exe：0000005：访问冲突读取位置0x6e61656a。
未处理的异常在0x104e8dcb在try_mysql_native.exe：0xC0000005：访问冲突读取位置0x6e61656a。
在0x104e8dcb在try_mysql_native.exe中的第一次机会异常：0xC0000005：访问冲突读取位置0x6e61656a。
未处理的异常在0x104e8dcb在try_mysql_native.exe：0xC0000005：访问冲突读取位置0x6e61656a。
在0x104e8dcb在try_mysql_native.exe中的第一次机会异常：0xC0000005：访问冲突读取位置0x6e61656a。
未处理的异常在0x104e8dcb在try_mysql_native.exe：0xC0000005：访问冲突读取位置0x6e61656a。
在0x104e8dcb在try_mysql_native.exe中的第一次机会异常：0xC0000005：访问冲突读取位置0x6e61656a。
未处理的异常在0x104e8dcb在try_mysql_native.exe：0xC0000005：访问冲突读取位置0x6e61656a。
在0x104e8dcb在try_mysql_native.exe中的第一次机会异常：0xC0000005：访问冲突读取位置0x6e61656a。
未处理的异常在0x104e8dcb在try_mysql_native.exe：0xC0000005：访问冲突读取位置0x6e61656a。
在0x104e8dcb在try_mysql_native.exe中的第一次机会异常：0xC0000005：访问冲突读取位置0x6e61656a。
未处理的异常在0x104e8dcb在try_mysql_native.exe：0xC0000005：访问冲突读取位置0x6e61656a。
在0x104e8dcb在try_mysql_native.exe中的第一次机会异常：0xC0000005：访问冲突读取位置0x6e61656a。
未处理的异常在0x104e8dcb在try_mysql_native.exe：0xC0000005：访问冲突读取位置0x6e61656a。
在0x104e8dcb在try_mysql_native.exe中的第一次机会异常：0xC0000005：访问冲突读取位置0x6e61656a。
未处理的异常在0x104e8dcb在try_mysql_native.exe：0xC0000005：访问冲突读取位置0x6e61656a。

解决方案

您确定任务列没有设置二进制排序规则吗？如果是，连接器可能会为同一列返回不同的元数据。

更新：

此外，请检查连接器是否已使用与项目相同的运行时进行编译。如果使用VS，我打赌另一个编译/ MT和其他与/ MD。这样，他们使用不同的堆，它不会工作。

I tried to connect C++ to MySql and I just can't get this to work properly. I used latest MySql and C++/Connector for Windows from Oracle site. I also use VS2010.

It compiles and everything works EXCEPT getString! I used the example that they supply with some tweaking:

#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");
        }
    }

... //the rest isn't relevant because it breaks here.

This is the output:

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 . . .

and this is what the table looks like so clearly it's not working properly. I just can't get it to get the strings which are varchar(120) from MySql:

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)

I tried VS2008 and this is what I get:

msvcp90d.dll!104e8dcb()
[Frames below may be incorrect and/or missing, no symbols loaded for msvcp90d.dll]
try_mysql_native.exe!std::operator<<(std::basic_ostream > & os={...}, const sql::SQLString & str={...}) Line 196 + 0x1f bytes C++ try_mysql_native.exe!main(int argc=1, const char * * argv=0x003e63e8) Line 115 + 0xa5 bytes C++ try_mysql_native.exe!__tmainCRTStartup() Line 586 + 0x19 bytes C try_mysql_native.exe!mainCRTStartup() Line 403 C kernel32.dll!7c817077()

and this:

'try_mysql_native.exe': Loaded 'C:\Documents and Settings\Eugene\My Documents\Visual Studio 2008\Projects\try_mysql_native\Debug\try_mysql_native.exe', Symbols loaded. 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\ntdll.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\kernel32.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\mysqlcppconn.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\libmysql.dll', Symbols loaded. 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\advapi32.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\rpcrt4.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\secur32.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\ws2_32.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\msvcrt.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\ws2help.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\WinSxS\x86_Microsoft.VC90.CRT_1fc8b3b9a1e18e3b_9.0.30729.4974_x-ww_d889290f\msvcp90.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\WinSxS\x86_Microsoft.VC90.CRT_1fc8b3b9a1e18e3b_9.0.30729.4974_x-ww_d889290f\msvcr90.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\WinSxS\x86_Microsoft.VC90.DebugCRT_1fc8b3b9a1e18e3b_9.0.30729.1_x-ww_f863c71f\msvcr90d.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\WinSxS\x86_Microsoft.VC90.DebugCRT_1fc8b3b9a1e18e3b_9.0.30729.1_x-ww_f863c71f\msvcp90d.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\mswsock.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\dnsapi.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\winrnr.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\wldap32.dll' 'try_mysql_native.exe': Loaded 'C:\Program Files\Bonjour\mdnsNSP.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\iphlpapi.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\user32.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\gdi32.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\imm32.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\rasadhlp.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\hnetcfg.dll' 'try_mysql_native.exe': Loaded 'C:\WINDOWS\system32\wshtcpip.dll' First-chance exception at 0x104e8dcb in try_mysql_native.exe: 0xC0000005: Access violation reading location 0x6e61656a. Unhandled exception at 0x104e8dcb in try_mysql_native.exe: 0xC0000005: Access violation reading location 0x6e61656a. First-chance exception at 0x104e8dcb in try_mysql_native.exe: 0xC0000005: Access violation reading location 0x6e61656a. Unhandled exception at 0x104e8dcb in try_mysql_native.exe: 0xC0000005: Access violation reading location 0x6e61656a. First-chance exception at 0x104e8dcb in try_mysql_native.exe: 0xC0000005: Access violation reading location 0x6e61656a. Unhandled exception at 0x104e8dcb in try_mysql_native.exe: 0xC0000005: Access violation reading location 0x6e61656a. First-chance exception at 0x104e8dcb in try_mysql_native.exe: 0xC0000005: Access violation reading location 0x6e61656a. Unhandled exception at 0x104e8dcb in try_mysql_native.exe: 0xC0000005: Access violation reading location 0x6e61656a. First-chance exception at 0x104e8dcb in try_mysql_native.exe: 0xC0000005: Access violation reading location 0x6e61656a. Unhandled exception at 0x104e8dcb in try_mysql_native.exe: 0xC0000005: Access violation reading location 0x6e61656a. First-chance exception at 0x104e8dcb in try_mysql_native.exe: 0xC0000005: Access violation reading location 0x6e61656a. Unhandled exception at 0x104e8dcb in try_mysql_native.exe: 0xC0000005: Access violation reading location 0x6e61656a. First-chance exception at 0x104e8dcb in try_mysql_native.exe: 0xC0000005: Access violation reading location 0x6e61656a. Unhandled exception at 0x104e8dcb in try_mysql_native.exe: 0xC0000005: Access violation reading location 0x6e61656a. First-chance exception at 0x104e8dcb in try_mysql_native.exe: 0xC0000005: Access violation reading location 0x6e61656a. Unhandled exception at 0x104e8dcb in try_mysql_native.exe: 0xC0000005: Access violation reading location 0x6e61656a.

解决方案

Are you sure task-column doesn't have the binary collation set? If so, the connector may return different metadata for the same column.

Update:

Also, check that the Connector has been compiled with the same runtime as your project. If using VS, I bet the other one was compiled with /MT and the other with /MD. This way, they use different heaps and it won't work.

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