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