/*********************************************************************** 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 #include 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; }