C API 连接MYSQL

#include <iostream>
#include <mysql.h>
#include <string>

#include <assert.h>


int main()
{
        // MYSQL 初始化
    MYSQL *ms_conn = mysql_init(NULL);
    if (ms_conn == NULL)
    {
        std::cout << "Error: mysql_init failed." << std::endl;
        return 0;
    }
    std::cout << "Info: mysql_init success." << std::endl;

    // 连接到MYSQL 数据库服务器，最后参数CLIENT_MULTI_STATEMENTS 指定SQL 可以同时多条。
    MYSQL *ms_temp = NULL;
    ms_temp = mysql_real_connect(ms_conn, "localhost", "root", "123456sx", 
            "suyh", 0, NULL, CLIENT_MULTI_STATEMENTS);
    if (ms_temp == NULL)
    {
        std::cout << "Error: mysql_real_connect() failed." << std::endl;
        mysql_close(ms_conn), ms_conn = NULL;
        return 0;
    }
    std::cout << "Info: mysql_real_connect() succect." << std::endl;

    std::string str_sqls = "";
    // str_sqls += "SELECT * FROM player_data WHERE id = 100000;";
    // str_sqls += "SELECT * FROM player_data WHERE id = 100001;";
    str_sqls += "SELECT * FROM player_data WHERE id = 100002";

    // 执行SQL 语句
    int res = 0;
    res = mysql_real_query(ms_conn, str_sqls.c_str(), str_sqls.size());
    if (res != 0)
    {
        std::cout << "Info: query failed, sql: " << str_sqls.c_str() << std::endl;
        mysql_close(ms_conn), ms_conn = NULL;
        return 0;
    }
    std::cout << "Info: query success." << std::endl;

    do
    {
        // 取出查询结果
        MYSQL_RES *ms_res = mysql_store_result(ms_conn);
        assert(ms_res != NULL);

        // 结果集中的字段个数
        unsigned int field_num = mysql_num_fields(ms_res);
        std::cout << "fileds number is " << field_num << std::endl;

        // 每个字段的结构
        MYSQL_FIELD* field = mysql_fetch_field(ms_res);
        assert(field != NULL);

        // 取出这个结果集中的结果
        MYSQL_ROW row_data = NULL;    // typedef char ** MYSQL_ROW;
        while (1)
        {
            row_data = mysql_fetch_row(ms_res);
            if (row_data == NULL)
                break;    // 结果集中已无数据

            // 一行结果中每个字段的字符数
            unsigned long *field_lens = mysql_fetch_lengths(ms_res);
            assert(field_lens != NULL);
            for (int i = 0; i < field_num; ++i)
            {
                /*
                std::cout << "field_lens[" << i << "] = " << field_lens[i]
                    << ", value is " << row_data[i] << std::endl;
                */
                std::cout << "field name: " << field[i].name;
                if (row_data[i] == NULL)
                    std::cout << ", value is NULL" << std::endl;
                else
                    // std::cout << ", value is " << row_data[i] << std::endl; 
                    std::cout << ", value is NOT NULL" << std::endl;
            }

            // ... // 处理结果
        }
    } while (mysql_next_result(ms_conn) == 0);

    mysql_close(ms_conn), ms_conn = NULL;
    return 0;
}