MySQL C++ 连接器：对“get_driver_instance”的未定义引用

Question

I've been trying to get the MySQL connector working I've installed both the connector and the mysql client library but I am still getting this error:

obj/Database.obj: In function `Database::connect()':
/home/xeross/alpine/src/server/Database.cpp:13: undefined reference to `get_driver_instance'
collect2: ld returned 1 exit status
make[2]: *** [alpine-server] Error 1
make[1]: *** [.build-conf] Error 2
make: *** [.build-impl] Error 2

Using Ubuntu 10.04 And my makefile is as follows:

INCLUDES = -I./src -I./src/shared
OUTDIR = bin
INTDIR = obj
OPTIONS = -ggdb -g3 -Wall -O0

alpine-server : Shared.a AsyncServerSocket.obj PlayerHandler.obj PacketHandler.obj     Session.obj User.obj Database.obj init
    g++ $(INCLUDES) $(OPTIONS) -static \
    -pthread \
    -lmysqlcppconn-static \
            -o $(OUTDIR)/alpine-server src/server/main.cpp \
        $(INTDIR)/AsyncServerSocket.obj \
        $(INTDIR)/PacketHandler.obj \
        $(INTDIR)/Database.obj \
        $(INTDIR)/PlayerHandler.obj \
        $(INTDIR)/Session.obj \
        $(INTDIR)/User.obj \
        $(INTDIR)/Shared.a \
        -lboost_system \
        -lmysqlclient


AsyncServerSocket.obj : src/server/AsyncServerSocket.cpp init
g++ -c $(INCLUDES) $(OPTIONS) -o $(INTDIR)/AsyncServerSocket.obj src/server/AsyncServerSocket.cpp

PlayerHandler.obj : src/server/PlayerHandler.cpp init
g++ -c $(INCLUDES) $(OPTIONS) -o $(INTDIR)/PlayerHandler.obj src/server/PlayerHandler.cpp

PacketHandler.obj : src/server/PacketHandler.cpp init
g++ -c $(INCLUDES) $(OPTIONS) -o $(INTDIR)/PacketHandler.obj src/server/PacketHandler.cpp

Session.obj : src/server/Session.cpp init
    g++ -c $(INCLUDES) $(OPTIONS) -o $(INTDIR)/Session.obj src/server/Session.cpp

User.obj : src/server/User.cpp init
    g++ -c $(INCLUDES) $(OPTIONS) -o $(INTDIR)/User.obj src/server/User.cpp

Database.obj : src/server/Database.cpp init
    g++ -c $(INCLUDES) $(OPTIONS) -o $(INTDIR)/Database.obj src/server/Database.cpp

# Shared.a
Shared.a : Packet.obj Flags.obj AsyncSocket.obj Log.obj init
    ar -cvq $(INTDIR)/Shared.a \
        $(INTDIR)/Packet.obj \
        $(INTDIR)/Flags.obj \
        $(INTDIR)/AsyncSocket.obj \
        $(INTDIR)/Log.obj
    ranlib $(INTDIR)/Shared.a

Packet.obj : src/shared/packet.cpp init
    g++ -c $(INCLUDES) $(OPTIONS) -o $(INTDIR)/Packet.obj src/shared/packet.cpp

Flags.obj : src/shared/Flags.cpp init
    g++ -c $(INCLUDES) $(OPTIONS) -o $(INTDIR)/Flags.obj src/shared/Flags.cpp

AsyncSocket.obj : src/shared/AsyncSocket.cpp init
g++ -c $(INCLUDES) $(OPTIONS) -o $(INTDIR)/AsyncSocket.obj src/shared/AsyncSocket.cpp

Log.obj : src/shared/Log.cpp init
    g++ -c $(INCLUDES) $(OPTIONS) -o $(INTDIR)/Log.obj src/shared/Log.cpp

init:
    mkdir -p bin obj

clean:
    rm -f $(INTDIR)/*.obj $(INTDIR)/*.a

The Code

// Excerpt from .hpp file
#include <cppconn/driver.h>
#include <cppconn/connection.h>
#include <cppconn/resultset.h>
#include <cppconn/statement.h>
// End excerpt

void Database::connect()
{
    std::stringstream connString;
    connString << "tcp://";
    connString << m_host;
    connString << ":";
    connString << m_port;

    m_driver = get_driver_instance(); // This guy is being a *****
    m_conn = m_driver->connect(connString.str(), m_user, m_password);
    m_conn->setSchema(m_database);
}

What can I do to fix this ?

Answer 1

Finally I could successfully compile a program with C++ connector in Ubuntu 10.10.

Initially I faced the same problem with "undefined reference to `get_driver_instance' " to solve this I declare my driver instance variable of MySQL_Driver type. For ready reference this type is defined in mysql_driver.h file. Here is the code snippet I used in my program.

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

and I compiled the program with -l mysqlcppconn linker option

Answer 2

Thank you so much, I got it fixed too. I had the exact experience.

I am using Eclipse CDT on 64 Bit CentOS and for anyone reading this here are the following steps .

1. first, be sure that the following are in the code.

include "mysql_driver.h"

include "mysql_connection.h"

using namespace sql::mysql;

2. Be sure that in Eclipse you have specified in your Eclipse project settings. the mysql/include and mysql/include/cppconn directories in your include and then also the mysql/lib in the library directory, then and more importantly you specify -lmysqlcppconn .

3. Be sure you got the -m64 set in the Eclipse compiler options too.

4. When you run your program, it may complain of missing libmysqlcppconn.so.1 . Do this, copy libmysqlcppconn.so.1.0.5 in your /usr/lib64 directory. Make a link of libmysqlcppconn.so.1 towards libmysqlcppconn.so.1.0.5 within that directory.

Your program should now run.

Answer 3

The code would be more helpful than the make file but try adding using namespace sql; to the top of Database.cpp.

// Excerpt from .hpp file
#include <cppconn/driver.h>
#include <cppconn/connection.h>
#include <cppconn/resultset.h>
#include <cppconn/statement.h>

using namespace sql;     // <---- add here

Answer 4

在使用该库中的东西的目标文件之后 ，您需要添加-lmysqlcppconn-static 。

Answer 5

You need to link with

-lmysqlcppconn -lmysqlcppconn-static

The first library contains the code for the headers in /usr/include/cppconn/ , and the second library contains the code found in the headers mysql_driver.h and mysql_connection.h .

Answer 6

To me was needed -lmysqlclient

g++ -o mariaS2json test.cpp -L/usr/lib/ -lmysqlcppconn -lmysqlclient

And now all works