c++ - 如何使用 C++ 连接 mySQL 数据库

Question

我正在尝试从我的网站连接数据库并使用 C++ 显示一些行。所以基本上我正在尝试制作一个从我的站点数据库中的表中执行选择查询的应用程序。现在，这一定是可能的，因为我已经看到大量的应用程序这样做了。

我该怎么做呢？有人可以举个例子告诉我应该使用哪些库吗？

Answer 1

在这里找到：

/* Standard C++ includes */
#include <stdlib.h>
#include <iostream>

/*
  Include directly the different
  headers from cppconn/ and mysql_driver.h + mysql_util.h
  (and mysql_connection.h). This will reduce your build time!
*/
#include "mysql_connection.h"

#include <cppconn/driver.h>
#include <cppconn/exception.h>
#include <cppconn/resultset.h>
#include <cppconn/statement.h>

using namespace std;

int main(void)
{
cout << endl;
cout << "Running 'SELECT 'Hello World!' »
   AS _message'..." << endl;

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

  /* Create a connection */
  driver = get_driver_instance();
  con = driver->connect("tcp://127.0.0.1:3306", "root", "root");
  /* Connect to the MySQL test database */
  con->setSchema("test");

  stmt = con->createStatement();
  res = stmt->executeQuery("SELECT 'Hello World!' AS _message"); // replace with your statement
  while (res->next()) {
    cout << "\t... MySQL replies: ";
    /* Access column data by alias or column name */
    cout << res->getString("_message") << endl;
    cout << "\t... MySQL says it again: ";
    /* Access column fata by numeric offset, 1 is the first column */
    cout << res->getString(1) << endl;
  }
  delete res;
  delete stmt;
  delete con;

} 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;
}

cout << endl;

return EXIT_SUCCESS;
}

Answer 2

最后，我可以在 Ubuntu 12.04 中使用 C++ 连接器成功编译程序我已经使用此命令安装了连接器

'apt-get install libmysqlcppconn-dev'

最初，我遇到了与“未定义对 `get_driver_instance' 的引用”相同的问题，为了解决这个问题，我声明了 MySQL_Driver 类型的驱动程序实例变量。为了便于参考，此类型在 mysql_driver.h 文件中定义。这是我在程序中使用的代码片段。

sql::mysql::MySQL_Driver *driver;
try {     
    driver = sql::mysql::get_driver_instance();
}

我用 -l mysqlcppconn 链接器选项编译了程序

并且不要忘记包含此标题

#include "mysql_driver.h" 

Answer 3

Yes, you will need the mysql c++ connector library. Read on below, where I explain how to get the example given by mysql developers to work.

Note(and solution): IDE: I tried using Visual Studio 2010, but just a few sconds ago got this all to work, it seems like I missed it in the manual, but it suggests to use Visual Studio 2008. I downloaded and installed VS2008 Express for c++, followed the steps in chapter 5 of manual and errors are gone! It works. I'm happy, problem solved. Except for the one on how to get it to work on newer versions of visual studio. You should try the mysql for visual studio addon which maybe will get vs2010 or higher to connect successfully. It can be downloaded from mysql website

Whilst trying to get the example mentioned above to work, I find myself here from difficulties due to changes to the mysql dev website. I apologise for writing this as an answer, since I can't comment yet, and will edit this as I discover what to do and find the solution, so that future developers can be helped.(Since this has gotten so big it wouldn't have fitted as a comment anyways, haha)

@hd1 link to "an example" no longer works. Following the link, one will end up at the page which gives you link to the main manual. The main manual is a good reference, but seems to be quite old and outdated, and difficult for new developers, since we have no experience especially if we missing a certain file, and then what to add.

@hd1's link has moved, and can be found with a quick search by removing the url components, keeping just the article name, here it is anyways: http://dev.mysql.com/doc/connector-cpp/en/connector-cpp-examples-complete-example-1.html

Getting 7.5 MySQL Connector/C++ Complete Example 1 to work

Downloads:

-Get the mysql c++ connector, even though it is bigger choose the installer package, not the zip.

-Get the boost libraries from boost.org, since boost is used in connection.h and mysql_connection.h from the mysql c++ connector

Now proceed:

-Install the connector to your c drive, then go to your mysql server install folder/lib and copy all libmysql files, and paste in your connector install folder/lib/opt

-Extract the boost library to your c drive

Next:

It is alright to copy the code as it is from the example(linked above, and ofcourse into a new c++ project). You will notice errors:

-First: change

cout << "(" << __FUNCTION__ << ") on line " »
 << __LINE__ << endl;

to

cout << "(" << __FUNCTION__ << ") on line " << __LINE__ << endl;

Not sure what that tiny double arrow is for, but I don't think it is part of c++

-Second: Fix other errors of them by reading Chapter 5 of the sql manual, note my paragraph regarding chapter 5 below

[Note 1]: Chapter 5 Building MySQL Connector/C++ Windows Applications with Microsoft Visual Studio If you follow this chapter, using latest c++ connecter, you will likely see that what is in your connector folder and what is shown in the images are quite different. Whether you look in the mysql server installation include and lib folders or in the mysql c++ connector folders' include and lib folders, it will not match perfectly unless they update the manual, or you had a magic download, but for me they don't match with a connector download initiated March 2014.

Just follow that chapter 5,

-But for c/c++, General, Additional Include Directories include the "include" folder from the connector you installed, not server install folder

-While doing the above, also include your boost folder see note 2 below

-And for the Linker, General.. etc use the opt folder from connector/lib/opt

*[Note 2]*A second include needs to happen, you need to include from the boost library variant.hpp, this is done the same as above, add the main folder you extracted from the boost zip download, not boost or lib or the subfolder "variant" found in boostmainfolder/boost.. Just the main folder as the second include

Next:

What is next I think is the Static Build, well it is what I did anyways. Follow it.

Then build/compile. LNK errors show up(Edit: Gone after changing ide to visual studio 2008). I think it is because I should build connector myself(if you do this in visual studio 2010 then link errors should disappear), but been working on trying to get this to work since Thursday, will see if I have the motivation to see this through after a good night sleep(and did and now finished :) ).

Answer 4

我必须在我的构建中包含 -lmysqlcppconn 才能让它工作。