使用SOCI c++数据库访问库的提升元组行集出现问题

在将元组行集与最新的soci和boost库一起使用时，出现编译错误。

我在网上找到了一个例子，但它没有用我使用的SOCI版本编译，这是最新的。

引起问题的部分是：

typedef std::vector<boost::tuple<double, double> > V;
soci::rowset<boost::tuple<double, double> > rows
        = sql.prepare << "select x(location),y(location) from cities";

以下是我从网上的一个例子中得到的完整代码：

#include <soci.h>
#include <soci-postgresql.h>
#include <boost/algorithm/string.hpp>
#include <boost/optional.hpp>
#include <boost/timer.hpp>
#include <boost/random.hpp>
#include <boost/tuple/tuple.hpp>
#include <iostream>
#include <istream>
#include <ostream>
#include <sstream>
#include <string>
#include <exception>
int main()
{
    try
    {
        soci::session sql(soci::postgresql, "dbname=ggl user=ggl password=ggl");
    int count;
    sql << "select count(*) from cities", soci::into(count);
    std::cout << "# Capitals: " << count << std::endl;
    typedef std::vector<boost::tuple<double, double> > V;
    soci::rowset<boost::tuple<double, double> > rows
        = sql.prepare << "select x(location),y(location) from cities";
    V vec;
    std::copy(rows.begin(), rows.end(), std::back_inserter(vec));
    for (V::const_iterator it = vec.begin(); it != vec.end(); ++it)
    {
        std::cout << it->get<0>() << " " << it->get<1>() << std::endl;
    }
}
catch (std::exception const &e)
{
    std::cerr << "Error: " << e.what() << 'n';
}
return 0;

}

它在以下线路上失败：

   soci::rowset<boost::tuple<double, double> > rows
            = sql.prepare << "select x(location),y(location) from cities";

这是一个我不太理解的错误：

   g++  -c  "/home/ubuntu/dev/testSoci/test.cpp" -g -O0 -Wall  -o ./Debug/test.o -I./include -I/home/ubuntu/dev/tools/QxOrm/include -I/usr/share/qt4/include -I/home/ubuntu/dev/tools/boost_1_48_0  -I. -I. -I/home/ubuntu/dev/tools/soci-3.1.0/core -I/home/ubuntu/dev/tools/soci-3.1.0/backends/postgresql -I/usr/include/postgresql -I/home/ubuntu/dev/tools/boost_1_48_0/boost 
In file included from /home/ubuntu/dev/tools/soci-3.1.0/core/into-type.h:13,
                 from /home/ubuntu/dev/tools/soci-3.1.0/core/blob-exchange.h:12,
                 from /home/ubuntu/dev/tools/soci-3.1.0/core/soci.h:18,
                 from /home/ubuntu/dev/testSoci/test.cpp:21:
/home/ubuntu/dev/tools/soci-3.1.0/core/exchange-traits.h: In instantiation of ‘soci::details::exchange_traits<boost::tuples::tuple<double, double, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> >’:
/home/ubuntu/dev/tools/soci-3.1.0/core/into.h:29:   instantiated from ‘soci::details::into_type_ptr soci::into(T&) [with T = boost::tuples::tuple<double, double, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type>]’
/home/ubuntu/dev/tools/soci-3.1.0/core/rowset.h:125:   instantiated from ‘soci::details::rowset_impl<T>::rowset_impl(const soci::details::prepare_temp_type&) [with T = boost::tuples::tuple<double, double, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type>]’
/home/ubuntu/dev/tools/soci-3.1.0/core/rowset.h:185:   instantiated from ‘soci::rowset<T>::rowset(const soci::details::prepare_temp_type&) [with T = boost::tuples::tuple<double, double, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type>]’
/home/ubuntu/dev/testSoci/test.cpp:51:   instantiated from here
/home/ubuntu/dev/tools/soci-3.1.0/core/exchange-traits.h:34: error: incomplete type ‘soci::details::exchange_traits<boost::tuples::tuple<double, double, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> >’ used in nested name specifier
make[1]: *** [Debug/test.o] Error 1

知道是什么原因吗？

非常感谢！Ludovic

一个解决方案是

1/添加括号soci:：rowset>行=（sql.prepare<<"从城市中选择x（位置），y（位置）"）；

2/做建议的答案：#include或#define