mysql api

MySQL 客户端 api (libmysqlclient-dev)的简单使用
几个常用重要接口

mysql_library_init()
mysql_library_end()
mysql_init()
mysql_connect() / mysql_real_connect()
mysql_query() / mysql_real_query()
mysql_num_fileds()
mysql_num_rows()
mysql_fetch_field() / mysql_fetch_fields()
mysql_fetch_row()
mysql_affected_row()

几个重要数据类型

MYSQL
MYSQL_RES
MYSQL_ROW
MYSQL_FIELD

编译选项

cmake

set(CMAKE_CXX_FLAGS “-g -lmysqlclient -pthread -lz -lm -lrt -ldl $CMAKE_CXX_FLAGS”)

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g++ build

g++ -o mysql -lmysqlclient -I/usr/include/mysql -L/usr/lib/x86_64-linux-gnu -pthread -lz -lm -lrt -ldl -g main.cc

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示例程序

小提示:

示例代码中使用到了另外两个三方库, 一个三方库时sspdlog

#include <sspdlog/sspdlog.h> 可以替换成 #include <iostream>,
SSPD_LOG_INFO可以替换为std::cout,
SSPD_LOG_ERROR可以替换为std::cerr

另一个三方库 为 自己的 工具库 oyoungs/dispatch, 可以到github上下载

#include <mysql/mysql.h>
#include <sspdlog/sspdlog.h>
#include <oyoung/format.hpp>

namespace mysql {
struct library {
library(int argc, char **argv, char **groups) {
if(mysql_library_init(argc, argv, groups)) {
throw std::runtime_error(“MYSQL Initialize failed”);
}
}

    ~library() {
        mysql_library_end();
    }
};

struct row {

    row(MYSQL_ROW row): m_row(row) {}


    ~row() {}

    operator bool() const {
        return m_row;
    }

    std::string operator[](std::size_t index) const {
        return m_row[index];
    }

    row(const row&) = delete;
    row(row&& other): m_row(other.m_row) {
        other.m_row = nullptr;
    }

private:
    MYSQL_ROW m_row{nullptr};
};

struct field {

    field(MYSQL_FIELD *field): m_field(field) {}

    std::string name() const {

        return m_field->name;
    }

    std::string catalog() const {
        return std::string(m_field->catalog, m_field->catalog_length);
    }



    ~field() {

    }

    field(const field&) = delete;
    field(field&& other): m_field(other.m_field) {
        other.m_field = nullptr;
    }

protected:
    MYSQL_FIELD *m_field{nullptr};
};

struct fields : field {

    fields(MYSQL_FIELD *f) : field(f) {}

    field operator[](std::size_t index) {
        return m_field + index;
    }
};

struct result {
    result() = default;
    result(MYSQL_RES *res): m_result(res) {}



    ~result() {
        if(m_result) {
            ::mysql_free_result(m_result);
        }
    }


    result(const result&) = delete;
    result(result&& other): m_result(other.m_result) {
        other.m_result = nullptr;
    }

    row fetch_row() {
        return mysql_fetch_row(m_result);
    }

    std::uint64_t rows() const {
        return mysql_num_rows(m_result);
    }

    unsigned field_count() const {
        return ::mysql_num_fields(m_result);
    }

    fields fetch_fields() {
        return mysql_fetch_fields(m_result);
    }




private:
    MYSQL_RES *m_result {nullptr};
};



struct client {
    client()
        : m_client(mysql_init(nullptr)) {

    }

    bool good() const {
        return nullptr != m_client;
    }

    bool not_good() const {
        return nullptr == m_client;
    }

    bool connect(const std::string& host, const std::string& user, const std::string& password, const std::string& database,
                 unsigned short port = 3306) {
        return mysql_real_connect(m_client, host.c_str(), user.c_str(), password.c_str(), database.c_str(), port, nullptr, 0) != nullptr;
    }

    bool query(const std::string& sql) {
        return mysql_real_query(m_client, sql.c_str(), sql.length()) == 0;
    }

    std::uint64_t affected_rows() const {
        return mysql_affected_rows(m_client);
    }

    std::uint64_t inserted_id() const {
        return mysql_insert_id(m_client);
    }

    result use_result() const {
        return result(mysql_use_result(m_client));
    }



    ~client() {

    }

    std::string error() const {
        return mysql_error(m_client);
    }

private:
    MYSQL *m_client;
};

}

int main(int argc, char**argv) try {

mysql::library library(argc, argv, nullptr);
mysql::client client{};

if(client.not_good()) {
    SSPD_LOG_ERROR << "Create MySQL client failed";
    return -1;
}

if(!client.connect("172.17.0.2", "blog", "blog.123", "blog")) {
    SSPD_LOG_ERROR << "MySQL connect failed: " << client.error();
    return -2;
}


if(!client.query("INSERT INTO user set name='blog', email='blog@hotmail.com'")) {
    SSPD_LOG_ERROR << "MySQL query INSERT failed: " << client.error();
    return -3;
}

SSPD_LOG_INFO << "MySQL affected rows after insert: " << client.affected_rows();
SSPD_LOG_INFO << "MySQL last inserted ID: " << client.inserted_id();


if(!client.query("SELECT id, name, email FROM user")) {
    SSPD_LOG_ERROR << "MySQL query SELECT failed: " << client.error();
    return -3;
}

auto result = client.use_result();

auto field_count = result.field_count();
auto fields      = result.fetch_fields();

while (auto row = result.fetch_row()) {
    for(auto i = 0; i < field_count; ++i) {
        SSPD_LOG_INFO << fields[i].name() << ": " << row[i];
    }
}

if(!client.query(oyoung::format("DELETE FROM user WHERE id=%1").arg(client.inserted_id()).to_string())) {
    SSPD_LOG_ERROR << "MySQL query DELETE failed: " << client.error();
    return -3;
}

SSPD_LOG_INFO << "MySQL affected rows after delete: " << client.affected_rows();


return 0;

} catch(const std::exception& e) {
SSPD_LOG_ERROR << e.what();
}

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版权声明：本文为优快云博主「逗神大人」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.youkuaiyun.com/oyoung_2012/article/details/101072215