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This is a very good cpp api for sybase, it works well in single cpp file, but when i include "sybase_driver.hpp" into a header file 'a.h', and an other file include the file 'a.h'。When complie&link the project, a link error has occurred:

LNK2005: "virtual struct vgi::dbconn::dbi::istatement * __thiscall vgi::dbconn::dbd::sybase::connection::get_statement(struct vgi::dbconn::dbi::iconnection &)" already defined

It seems to point to the end of the file sybase_driver.hpp:

dbi::istatement* connection::get_statement(dbi::iconnection& iconn)
{
return new statement(dynamic_cast<connection&>(iconn));
}

So， how to solve the problem? Thank you!

I separate this function from the file to a .cpp file, and then add all this files to project.
This can solve the link error.

When i fetch a little amount of data, the strings returned are correct. But when the volume of records increases, most of the data(datatype CS_CHAR_TYPE) behind is incorrect: correct string followed by garbled.

I'm not familiar with Sybase APIs, and made some changes in sybase_driver.hpp.

1, below the function 'ct_describe' about line 620, I add this:
if (columns[i].datatype == CS_CHAR_TYPE) { columns[i].format = CS_FMT_PADNULL; }

2, comments 2 lines at line 196:
//if (CS_ROW_FAIL == retcode)
// throw std::runtime_error(std::string(FUNCTION).append(": Error fetching row ").append(std::to_string(result)));

3, In function "void process_result(bool compute, bool bind)" about line 645, add 3 lines:
if (columns[i].datatype == CS_CHAR_TYPE)
columndata[i].allocate(columns[i].maxlength + 2);
else
columndata[i].allocate(columns[i].maxlength);

4, Commented on the associated exception about line 710

After 4 steps, it works in debug mode(crashed in release mode), but still throw exceptions in callback functions, so i comment cs_msg_callback, ct_msg_callback and srv_msg_callback in the constructor of driver.

While this can get the right results, I'm not sure it's the right approach, and are there other better ways to fix it?

Thank you!