Question

我在c＃中尝试了autocomplete文字，我尝试了这段代码，

try
{
   textBox1.AutoCompleteMode = AutoCompleteMode.Suggest;
   textBox1.AutoCompleteSource = AutoCompleteSource.CustomSource;
   AutoCompleteStringCollection col = new AutoCompleteStringCollection();
   sqlconn.Open();
   string query = "select id from cmp_det where id =" + textBox1.Text;
   SqlCommand command = new SqlCommand(query, sqlconn);
   SqlDataReader sdr = command.ExecuteReader();
   while (sdr.Read())
   {
       col.Add(sdr["Column_Name"].ToString());    
   }
   sdr.Close();
   textBox1.AutoCompleteCustomSource = col;
   sqlconn.Close();
}
catch(Exception ex)
{
    Console.WriteLine("exception=="+ex);
}

when）执行代码时出现以下错误：

exception==System.InvalidOperationException: There is already an open DataReader associated with this Command which must be closed first.

Answer 1

尝试替换您的代码：

SqlDataReader sdr = command.ExecuteReader();
while (sdr.Read())
{
   col.Add(sdr["Column_Name"].ToString());    
}
sdr.Close();

到此：

using(SqlDataReader sdr = command.ExecuteReader())
{
   while (sdr.Read())
   {
       col.Add(sdr.GetValue(0).ToString());    
   }
}

其中0是查询的从零开始的列序号

Answer 2

启用MARS会解决此问题吗？将"MultipleActiveResultSets=True"添加到连接字符串应解决该类型的错误。

http://msdn.microsoft.com/en-us/library/h32h3abf(v=vs.80).aspx

Answer 3

这是因为MAR的默认设置发生了变化。它曾经默认打开，我们默认将其更改为关闭后RC1。因此，只需更改连接字符串即可将其添加回来（将MultipleActiveResultSets = True添加到连接字符串中）。

c＃中的自动填充文本框

3 个答案: