Question

我有这段代码，

class DbUpdater 
{

private:

MYSQL mysql;
MYSQL *connection;

int connect() 
{
    mysql_init(&mysql);
    this->connection = mysql_real_connect(&mysql, "localhost", "root", "password", "dbname", 0, 0, CLIENT_MULTI_STATEMENTS);
    if (this->connection == NULL) 
    {
     printf(mysql_error(&mysql));
     return 0;
    }

    mysql_set_character_set(connection, "utf8");
    return 1;
}

vector <TrackingHistory*> getTrackingHistoryByNumber(string number) 
{
    MYSQL_RES *result;
    MYSQL_ROW row;

   string query = "SELECT * FROM tracking_history WHERE number = '" + number + "' ORDER BY date DESC;";

    int state = mysql_query(this->connection, query.c_str());
    result = mysql_store_result(this->connection);

    vector <TrackingHistory*> trackingHistory;

    int numRows = mysql_num_rows(result);

    while ((row = mysql_fetch_row(result)) != NULL) {

    TrackingHistory *item = new TrackingHistory(atoi(row[0]), atoi(row[1]), string(row[2]), string(row[3]),
        string(row[4]), string(row[5]), string(row[6]), string(row[7]), string(row[8]), string(row[9]));

    trackingHistory.push_back(item);
    }
    mysql_free_result(result);
    return trackingHistory;
}

public:

DbUpdater() 
{
    this->connect();
}

void UpdateDB(vector <HistoryItem*> historyItems) 
{
        vector <TrackingHistory*> trackingHistory = this->getTrackingHistoryByNumber( historyItems[0]->Number);
}

};

因此，我创建了类DbUpdater的实例，只需调用方法UpdateDb()

我在函数getTrackingHistoryByNumber()

中有一个奇怪的行为

int numRows = mysql_num_rows(result);，此行会抛出段错误。只有在一个连接中执行多个查询时才会发生这种情况。如果我在每次迭代后重新连接，所有查询都可以。

例如，我有10个查询。当我第一次启动程序时，它会在第二次查询时抛出段错误。下一步将在第三次查询时抛出segfault。接下来的开始会在第4次查询时抛出它。

我在ubuntu 12.04中使用repos中的libmysql

这可能是什么原因？

~~谢谢你，对不起我的英语。~~

一个连接中的mysql c ++分段错误

0 个答案: