c急剧的数据库连接问题 [英] c sharp database connection problem

问题描述

我有关于数据库连接的问题。请帮助我这方面

代码是

i have problem about database connectivity.please help me this regard
code is

private void button5_Click(object sender, EventArgs e)
        {
            string str = @"Data Source=J:\BerendinaSW\Payment20150408\Payment2015\Social.sdf;Persist Security Info=True";

            SqlConnection con = new SqlConnection(str);
           try{
            con.Open();
           }
            catch(Exception ){

                MessageBox.Show("cannot connect");
            }
           SqlCommand cm = new SqlCommand("SELECT * FROM [admin]",con);
           cm.Connection = con;
           SqlDataReader reader = null;
           reader = cm.ExecuteReader(); // error showing in here it is mentioning connection closed
           while (reader.Read())
           {
               if (textBox1.Text ==(reader["username"].ToString())  && textBox2.Text == (reader["password"].ToString()))
               {
                   label8.Visible = true;
               }
               else
               {
                   label9.Visible = true;
                   textBox1.Text = "";
                   textBox2.Text = "";
               }
           }
        }

推荐答案

这是一个SDF文件，而不是SQL Server数据库。

使用SQLCE类而不是SQL服务器：

SqlCeConnection [ ^ ]

SqlCeCommand [ ^ ]

等等。

That's an SDF file, not a SQL Server database.
Use SQLCE classes instead of SQL server:
SqlCeConnection[^]
SqlCeCommand[^]
And so forth.

请使用此..

Please use this ..

private void button5_Click(object sender, EventArgs e)
        {
            string str = @"Data Source=J:\BerendinaSW\Payment20150408\Payment2015\Social.sdf;Persist Security Info=True";
 
            SqlConnection con = new SqlConnection(str);
           try{
            con.Open();
           }
            catch(Exception ){
 
                MessageBox.Show("cannot connect");
            }
           SqlCommand cm = new SqlCommand("SELECT * FROM [admin]",con);
           
           SqlDataReader reader = null;
           con.Open();
           reader = cm.ExecuteReader(); 
           con.Close();
           while (reader.Read())
           {
               if (textBox1.Text ==(reader["username"].ToString())  && textBox2.Text == (reader["password"].ToString()))
               {
                   label8.Visible = true;
               }
               else
               {
                   label9.Visible = true;
                   textBox1.Text = "";
                   textBox2.Text = "";
               }
           }
        }

谢谢

AARIF SHAIKH

Thanks
AARIF SHAIKH

private void button5_Click（object sender，EventArgs e）

{

string str = @数据源= J：\ BeendinaSW \ Payment20150408 \Payment2015 \Social.sdf; Persist Security Info = True;



SqlConnection con = new SqlConnection（str ）;

尝试{



if（con.State == ConnectionState.Open）

con.Close （）;

con.Open（）;

}

catch（例外）{



MessageBox.Show（无法连接）;

}

SqlCommand cm = new SqlCommand（SELECT * FROM [admin]，con）;

cm.Connection = con;

SqlDataReader reader = null;

reader = cm.ExecuteReader（）; //错误显示在这里它提到连接关闭

而（reader.Read（））

{

if（textBox1.Text = =（reader [username]。ToString（））&& textBox2.Text ==（reader [password]。ToString（）））

{

label8 .Visible = true;

}

else

{

label9.Visible = true;

textBox1.Text =;

textBox2.Text =;

}

}

}

private void button5_Click(object sender, EventArgs e)
{
string str = @"Data Source=J:\BerendinaSW\Payment20150408\Payment2015\Social.sdf;Persist Security Info=True";

SqlConnection con = new SqlConnection(str);
try{

if(con.State==ConnectionState.Open)
con.Close();
con.Open();
}
catch(Exception ){

MessageBox.Show("cannot connect");
}
SqlCommand cm = new SqlCommand("SELECT * FROM [admin]",con);
cm.Connection = con;
SqlDataReader reader = null;
reader = cm.ExecuteReader(); // error showing in here it is mentioning connection closed
while (reader.Read())
{
if (textBox1.Text ==(reader["username"].ToString()) && textBox2.Text == (reader["password"].ToString()))
{
label8.Visible = true;
}
else
{
label9.Visible = true;
textBox1.Text = "";
textBox2.Text = "";
}
}
}

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