MYSQL C API : CLIENT_MULTI_STATEMENTS 选项

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

#include <assert.h>



int main()
{
    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;

    // 参数CLIENT_MULTI_STATEMENTS 指定一次query 可以执行多条SQL
    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;
        std::cout << mysql_error(ms_conn) << 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 id, account, sex, level, powers FROM player_data WHERE id = 100000";
    str_sqls += ";";
    str_sqls += "SELECT id, account, sex, level, powers FROM player_data WHERE id = 100001";
    str_sqls += ";";
    str_sqls += "SELECT id, account, sex, level, powers FROM player_data WHERE id = 100002";

    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;
        std::cout << mysql_error(ms_conn) << std::endl;
    }
    else
    {
        std::cout << "Info: query success." << std::endl;
        std::cout << std::endl;

        // CLIENT_MULTI_STATEMENTS 指定该选项需要mysql_next_result() 函数来获取下一条结果集
        // 如果结果集未取完，则不能进行query 操作。
        do
        {
            MYSQL_RES *ms_res = mysql_store_result(ms_conn);
            assert(ms_res != NULL);

            unsigned int field_num = mysql_num_fields(ms_res);
            std::cout << "fileds number is " << field_num << std::endl;

            MYSQL_FIELD* field_info = mysql_fetch_field(ms_res);
            assert(field_info != NULL);

            MYSQL_ROW row_data = NULL;
            while (1)
            {
                row_data = mysql_fetch_row(ms_res);
                if (row_data == NULL)
                    break;

                unsigned long *field_lens = mysql_fetch_lengths(ms_res);
                assert(field_lens != NULL);
                for (int i = 0; i < field_num; ++i)
                {
                    if (field_info[i].type == MYSQL_TYPE_BLOB)
                    {
                        std::cout << "current filed type is BLOB." << std::endl;
                        continue;
                    }

                    if (row_data[i] == NULL)
                    {
                        std::cout << "field_lens[" << i << "] = " << field_lens[i]
                            << ", value is NULL." << std::endl;
                    }
                    else
                    {
                        std::cout << "field_lens[" << i << "] = " << field_lens[i] 
                            << ", value is " << row_data[i] << std::endl;
                    }
                }
            }

            mysql_free_result(ms_res), ms_res = NULL;

            std::cout << "#######################################" << std::endl;
        } while (mysql_next_result(ms_conn) == 0);
    }



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