使用 MySqlDataReader 读取 [英] Reading with MySqlDataReader

问题描述

您好，我在使用 MySqlDataReader 阅读时遇到问题.我尝试将 while() 更改为 if() 并且它起作用了.所以我在 while (Reader.Read()) 上做错了.谢谢你的回答.(今天的另一个问题已解决，评论的人帮助了我xd)

Hello I'm having problem to read with MySqlDataReader. I've tried to change while() to if() and it worked then. So I'm doing something wrong with while (Reader.Read()). Thanks for answer. ( The other question today is fixed, someone that commented helped me xd )

using (MySqlCommand cmd = new MySqlCommand
      ("SELECT * FROM `citationer`",  mysqlCon))
{
    try
    {
        MySqlDataReader Reader = cmd.ExecuteReader();
        while (Reader.Read()) // this part is wrong somehow
        {
            citationstexter.Add(Reader.GetString(loopReading)); // this works
            loopReading++; // this works
        }
        Reader.Close();
    }

    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

推荐答案

您的问题是将 loopReading 参数用于 GetString.此参数应该是从零开始的列序号(列号)，但您要为读取的每一行增加它.

Your problem is the use of the loopReading parameter to GetString. This parameter should be the zero-based column ordinal (the column number), but you're incrementing it for every row you read.

请参阅此处了解更多信息:http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqldatareader.getstring.aspx

See here for more info: http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqldatareader.getstring.aspx

您应该将 0 用于引文表的第一列，1 用于第二列，以此类推.

You should use 0 for the first column of your citationer table, 1 for the second column, etc.

另外，使用

  using(MySqlDataReader Reader = cmd.ExecuteReader()) 
  {
    ...
  }

就像您为 mySqlCommand 对象所做的那样，以防止内存泄漏(但这不是您的问题.)

just like you did for the mySqlCommand object to save a memory leak (but this is not your problem.)

这篇关于使用 MySqlDataReader 读取的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！