C ++ MySQL插入數據庫

Question

這是我的代碼，我試圖在數據庫中的sma中插入ma，但是發生錯誤的原因是：在mysql.h的mysql.h行中聲明了太多的函數'int mysql_query（MYSQL *，const char *）'注意： int STDCALL mysql_query（MYSQL * mysql，const char * q）;

while(true)
    {
        mysql_query(conn, " select close, id from fivemin order by id DESC LIMIT 5 ");
    result = mysql_store_result(conn);
    num_fields = mysql_num_fields(result);
    float sum = 0;
    while((row=mysql_fetch_row(result)))
        {
                 sum += atof(row[0]);
                 last_id = atoi(row[1]);

        }
    float ma;
    ma=sum/5.0;
    if(previous_last_id != last_id)
        {
        cout << "Simple moving Average: " << ma << endl;
        previous_last_id = last_id;
        }

     mysql_query(conn,("insert into sma values('%f')"),ma);
    Sleep(1000);
}

Answer 1

mysql_query(conn,("insert into sma values('%f')"),ma)有三個參數。

您需要先格式化字符串，然后才能調用mysql_query.

例：

char str[80];
sprintf(str, "insert into sma values('%f')", ma);
mysql_query(conn, str);