Question

我是c ++的初学者，并认为我要学习的唯一方法就是弄脏一些代码。我正在尝试构建一个连接到mysql数据库的程序。我在linux上使用g ++。没有想法。

我运行“make”，这是我的错误：

hello.cpp:38: error: ‘get_driver_instance’ is not a member of ‘sql::mysql’
make: *** [hello.o] Error 1

这是我的代码，包括makefile。任何帮助都会很棒！提前致谢

###BEGIN hello.cpp###

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

#include "mysql_connection.h"

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

#define EXAMPLE_HOST "localhost"
#define EXAMPLE_USER "root"
#define EXAMPLE_PASS ""
#define EXAMPLE_DB "world"

using namespace std;
using namespace sql::mysql;

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);

    cout << "Connector/C++ tutorial framework..." << endl;
    cout << endl;


    try { 
        sql::Driver *driver;
        sql::Connection *con;
        sql::Statement  *stmt;
        driver = sql::mysql::get_driver_instance();
        con = driver->connect("tcp://127.0.0.1:3306", "user", "password");
        stmt = con->createStatement();
        stmt->execute("USE " EXAMPLE_DB);
        stmt->execute("DROP TABLE IF EXISTS test");
        stmt->execute("CREATE TABLE test(id INT, label CHAR(1))");
        stmt->execute("INSERT INTO test(id, label) VALUES (1, 'a')");
        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;
    }

    cout << "Done." << endl;
    return EXIT_SUCCESS;
}
###END hello.cpp###

###BEGIN Make File###
SRCS     := hello.cpp
OBJS     := $(SRCS:.cpp=.o)
CXXFLAGS := -Wall -pedantic
INCPATHS := -I/home/user/mysql-connector/include/
LIBPATHS := -L/home/user/mysql-connector/lib/ -L/home/user/mysql-connector-c/lib/
LIBS     := -static -lmysqlclient -mysqlcppconn-static
EXE      := MyExecutable



$(EXE): $(OBJS)
    $(CXX) $(OBJS) $(LIBPATHS) $(LIBS) -o $@

.cpp.o:
    $(CXX) $(CXXFLAGS) $(INCPATHS) -c $< -o $@

###End Makefile###

Answer 1

你的问题在这里，get_driver_instance不是sql :: mysql的成员，所以修复这个删除sql :: mysql ::它会起作用

更改此行

driver = sql::mysql::get_driver_instance();

到这个

 driver = get_driver_instance();

查看此处的examples

Answer 2

包括：??

#include "mysql_driver.h"

Answer 3

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，我遇到了同样的问题，“未定义引用`get_driver_instance'”来解决这个问题我声明了我的MySQL_Driver类型的驱动程序实例变量。对于准备参考，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 4

看起来该函数在全局命名空间中，不在sql::mysql::

前面

mysql-connector-c ++ - 'get_driver_instance'不是'sql :: mysql'的成员

4 个答案: