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ade68d172d
Replaced std::nullptr_t for boost::variant2::monostate in values Added support for relational operators in value Automatic docs generation closes #48 closes #46
102 lines
4.0 KiB
C++
102 lines
4.0 KiB
C++
//
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// Copyright (c) 2019-2021 Ruben Perez Hidalgo (rubenperez038 at gmail dot com)
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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//[example_metadata
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#include "boost/mysql/mysql.hpp"
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#include <boost/asio/io_context.hpp>
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#include <boost/system/system_error.hpp>
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#include <iostream>
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#define ASSERT(expr) \
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if (!(expr)) \
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{ \
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std::cerr << "Assertion failed: " #expr << std::endl; \
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exit(1); \
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}
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void main_impl(int argc, char** argv)
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{
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if (argc != 3)
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{
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std::cerr << "Usage: " << argv[0] << " <username> <password>\n";
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exit(1);
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}
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// Connection params (host, port, user, password, database)
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boost::asio::ip::tcp::endpoint ep (boost::asio::ip::address_v4::loopback(), boost::mysql::default_port);
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boost::mysql::connection_params params (argv[1], argv[2], "boost_mysql_examples");
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// TCP and MySQL level connect
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boost::asio::io_context ctx;
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boost::mysql::tcp_connection conn (ctx);
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conn.connect(ep, params);
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// Issue the query
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const char* sql = R"(
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SELECT comp.name AS company_name, emp.id AS employee_id
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FROM employee emp
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JOIN company comp ON (comp.id = emp.company_id)
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)";
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boost::mysql::tcp_resultset result = conn.query(sql);
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/**
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* Resultsets allow you to access metadata about the fields in the query
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* using the fields() function, which returns a vector of field_metadata
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* (one per field in the query, and in the same order as in the query).
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* You can retrieve the field name, type, number of decimals,
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* suggested display width, whether the field is part of a key...
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*/
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ASSERT(result.fields().size() == 2);
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const boost::mysql::field_metadata& company_name = result.fields()[0];
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ASSERT(company_name.database() == "boost_mysql_examples"); // database name
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ASSERT(company_name.table() == "comp"); // the alias we assigned to the table in the query
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ASSERT(company_name.original_table() == "company"); // the original table name
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ASSERT(company_name.field_name() == "company_name"); // the name of the field in the query
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ASSERT(company_name.original_field_name() == "name"); // the name of the physical field in the table
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ASSERT(company_name.type() == boost::mysql::field_type::varchar); // we created the field as a VARCHAR
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ASSERT(!company_name.is_primary_key()); // field is not a primary key
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ASSERT(!company_name.is_auto_increment()); // field is not AUTO_INCREMENT
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ASSERT(company_name.is_not_null()); // field may not be NULL
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const boost::mysql::field_metadata& employee_id = result.fields()[1];
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ASSERT(employee_id.database() == "boost_mysql_examples"); // database name
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ASSERT(employee_id.table() == "emp"); // the alias we assigned to the table in the query
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ASSERT(employee_id.original_table() == "employee"); // the original table name
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ASSERT(employee_id.field_name() == "employee_id"); // the name of the field in the query
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ASSERT(employee_id.original_field_name() == "id"); // the name of the physical field in the table
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ASSERT(employee_id.type() == boost::mysql::field_type::int_); // we created the field as INT
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ASSERT(employee_id.is_primary_key()); // field is a primary key
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ASSERT(employee_id.is_auto_increment()); // we declared the field as AUTO_INCREMENT
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ASSERT(employee_id.is_not_null()); // field cannot be NULL
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// Close the connection
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conn.close();
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}
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int main(int argc, char** argv)
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{
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try
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{
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main_impl(argc, argv);
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}
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catch (const boost::system::system_error& err)
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{
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std::cerr << "Error: " << err.what() << ", error code: " << err.code() << std::endl;
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return 1;
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}
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catch (const std::exception& err)
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{
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std::cerr << "Error: " << err.what() << std::endl;
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return 1;
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}
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}
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//]
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