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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")

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

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 , 可以到github上下载

#include 
   
    #include 
    
     #include 
     
      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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