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/***********************************************************************
fieldinf.cpp - Shows how to request information about the fields in a
table, such as their SQL and C++-equivalent types.
Copyright (c) 1998 by Kevin Atkinson, (c) 1999-2001 by MySQL AB, and
(c) 2004-2009 by Educational Technology Resources, Inc. Others may
also hold copyrights on code in this file. See the CREDITS.txt file
in the top directory of the distribution for details.
This file is part of MySQL++.
MySQL++ is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published
by the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
MySQL++ is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public
License along with MySQL++; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
USA
***********************************************************************/
#include "cmdline.h"
#include "printdata.h"
#include <iostream>
#include <iomanip>
using namespace std;
int
main(int argc, char *argv[])
{
// Get database access parameters from command line
mysqlpp::examples::CommandLine cmdline(argc, argv);
if (!cmdline) {
return 1;
}
try {
// Establish the connection to the database server.
mysqlpp::Connection con(mysqlpp::examples::db_name,
cmdline.server(), cmdline.user(), cmdline.pass());
// Get contents of main example table
mysqlpp::Query query = con.query("select * from stock");
mysqlpp::StoreQueryResult res = query.store();
// Show info about each field in that table
char widths[] = { 12, 22, 46 };
cout.setf(ios::left);
cout << setw(widths[0]) << "Field" <<
setw(widths[1]) << "SQL Type" <<
setw(widths[2]) << "Equivalent C++ Type" <<
endl;
for (size_t i = 0; i < sizeof(widths) / sizeof(widths[0]); ++i) {
cout << string(widths[i] - 1, '=') << ' ';
}
cout << endl;
for (size_t i = 0; i < res.field_names()->size(); i++) {
// Suppress C++ type name outputs when run under dtest,
// as they're system-specific.
const char* cname = res.field_type(int(i)).name();
mysqlpp::FieldTypes::value_type ft = res.field_type(int(i));
ostringstream os;
os << ft.sql_name() << " (" << ft.id() << ')';
cout << setw(widths[0]) << res.field_name(int(i)).c_str() <<
setw(widths[1]) << os.str() <<
setw(widths[2]) << cname <<
endl;
}
cout << endl;
// Simple type check
if (res.field_type(0) == typeid(string)) {
cout << "SQL type of 'item' field most closely resembles "
"the C++ string type." << endl;
}
// Tricky type check: the 'if' path shouldn't happen because the
// description field has the NULL attribute. We need to dig a
// little deeper if we want to ignore this in our type checks.
if (res.field_type(5) == typeid(string)) {
cout << "Should not happen! Type check failure." << endl;
}
else if (res.field_type(5) == typeid(mysqlpp::sql_blob_null)) {
cout << "SQL type of 'description' field resembles "
"a nullable variant of the C++ string type." << endl;
}
else {
cout << "Weird: fifth field's type is now " <<
res.field_type(5).name() << endl;
cout << "Did something recently change in resetdb?" << endl;
}
}
catch (const mysqlpp::BadQuery& er) {
// Handle any query errors
cerr << "Query error: " << er.what() << endl;
return -1;
}
catch (const mysqlpp::Exception& er) {
// Catch-all for any other MySQL++ exceptions
cerr << "Error: " << er.what() << endl;
return -1;
}
return 0;
}
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