C# SqlDataReader = null？
C# SqlDataReader = null？
提问于 2010-03-23 22:39:58
String sqlCheckPass =
"Select * from Login where Username like @Username and Password like @Password";
SqlCommand SqlCom = new SqlCommand(sqlCheckPass, myConnection);
SqlCom.Parameters.Add(new SqlParameter("@Username", sUserName));
SqlCom.Parameters.Add(new SqlParameter("@Password", sPassword));
myConnection.Open();
SqlDataReader myreader;
myreader = SqlCom.ExecuteReader();
int id = -1;
ErrorBox.InnerHtml = "Username:" + sUserName + ":" + sPassword + ":<br/>";
while (myreader.HasRows)
{
id = (int)myreader["id"];
String sUser = (String)myreader["Username"];
String sPass = (String)myreader["Password"];
ErrorBox.InnerHtml += "UserId is <b>" + id + "</b> " + sUser + ":" + sPass + ":<br >";
Session["LoginID"] = id;
Server.Transfer(ReturnPage);
}
if (id == -1)
{
ErrorBox.InnerHtml = "Incorrect Password";
}
myConnection.Close();
catch (Exception err)
{
ErrorBox.InnerHtml = "Error Getting Option ID" + err.Message;
}我在myreader =SqlCom.ExecuteReader()处添加了一个断点，它一直将myreader作为null和HasRows = False返回，但它确实有行。因此，它会一直验证我的登录是否不正确，因为id = -1，
帮助?
回答 3
Stack Overflow用户
发布于 2010-03-23 22:44:27
您没有将您的阅读器连接到您的SQL连接/命令吗？
SqlConnection myConnection = new SqlConnection(myConnectionString);
SqlCommand myCommand = new SqlCommand(mySelectQuery, myConnection);
myConnection.Open();
SqlDataReader myReader = myCommand.ExecuteReader(CommandBehavior.CloseConnection);
while(myReader.Read())
{
Console.WriteLine(myReader.GetString(0));
}
myReader.Close();Stack Overflow用户
发布于 2010-03-23 23:02:13
问题可能类似于SqlParameters查询中的问题。试一试
String sqlCheckPass =
"Select * from Login where Username like '%' + @Username + '%' and Password like '%' + @Password + '%'"; Stack Overflow用户
发布于 2010-03-23 23:32:24
Bryan Denny上面的回答是正确的，但是，我将使用如下所示的语句将所有代码包含在其中：
using (SqlConnection dataConnection = new SqlConnection(connectionString))
{
using (SqlCommand SqlCom = dataConnection.CreateCommand())
{
SqlCom.CommandText = "Select * from Login where Username like @Username and Password like @Password";
SqlCom.Parameters.Add(new SqlParameter("@Username", sUserName));
SqlCom.Parameters.Add(new SqlParameter("@Password", sPassword));
dataConnection.Open();
SqlDataReader myreader;
myreader = SqlCom.ExecuteReader();
dataConnection.Close();
}
}我没有把你所有的代码都添加到这个代码片段中，我想你已经明白了。
此外，您还可以尝试修改select语句以返回记录数，因为这是您需要的所有内容：
SELECT COUNT(*) FROM Login WHERE Username like @Username AND Password like @Password祝好运!
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/2500747
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