记录已成功插入，但数据库未更新C＃和SQL Server Compact数据库

Question

private void button1_Click(object sender, EventArgs e)
{
        string usernames = textBox1.Text;
        string passwords = textBox2.Text;
        string emailid = textBox5.Text;
        string telno = textBox6.Text;

        string connectionstring = "Data Source=|DataDirectory|\\libdb.sdf; Persist Security Info=False ;";
        using (SqlCeConnection con = new SqlCeConnection(connectionstring))
        {
            con.Open();

            using (SqlCeCommand Query = new SqlCeCommand("INSERT INTO Registers " + "(usernames,passwords,emailid,telno) " + "VALUES (@usernames,@passwords,@emailid,@telno)", con))
            {

                Query.Parameters.AddWithValue("@usernames", usernames);
                Query.Parameters.AddWithValue("@passwords", passwords);
                Query.Parameters.AddWithValue("@emailid", emailid);
                Query.Parameters.AddWithValue("@telno", telno);
                Query.ExecuteNonQuery();
            }
            MessageBox.Show("QueryExecuted");
            con.Close();
            MessageBox.Show("Closedconnecrion");
            con.Dispose();
            MessageBox.Show("disposed");
            this.Close();

            /*string conString = "Data Source=" + 
            Path.Combine(
                   Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData),
                   "MyAppData\\database.sdf") + ";Password=yourPassword;";
             even  this method dosent works */
        }

    }
}

on executing this code I find it executes successfully. But when I go and check the database, I find the entries empty...

I even tried refreshing database..

1. I didn't find problem in connectivity.
2. Query no error executed successfully.

The problem is I didn't find result or the data I gave as input in database.

Please be descriptive with code eg and mail to scarlet.gabriel@gmail.com

Answer 1

Test your connection with the database first, You can get the connection string by creating the udl file.

1. create a textfile and savaas it with the extension udl (example connection.udl).
2. double click and run this file.
3. a window will be opened where you can get the option for getting the connection string.
4. after testing the connection, close this window and open this file with a note pad.

5. copy the connection string and paste it in the below statement.

     string connectionstring =" paste here"; 

Answer 2

How can you be sure if the connection is open and has done the job? Use try... catch block to catch if any error occurs:

using (SqlCeConnection con = new SqlCeConnection(connectionstring))
    {
       try{con.Open();}
       catch(Exception ex)
       {
         // database connection error. log/display ex. > return.
       }

       if(con.State==ConnectionState.Open)
       { 
         using (SqlCeCommand Query = new SqlCeCommand("INSERT INTO Registers " + "(usernames,passwords,emailid,telno) " + "VALUES (@usernames,@passwords,@emailid,@telno)", con))
         {

            Query.Parameters.AddWithValue("@usernames", usernames);
            Query.Parameters.AddWithValue("@passwords", passwords);
            Query.Parameters.AddWithValue("@emailid", emailid);
            Query.Parameters.AddWithValue("@telno", telno);
            try{
                Query.ExecuteNonQuery();
               }
            catch(Exception ex)
               {
                  // database communication error. log/display ex
               }
         }
           MessageBox.Show("QueryExecuted");
        }
        if(con.State==ConnectionState.Open)
        { 
           try{con.Close();}
           catch{}
         }

    }

Answer 3

Instead of using connectionstring = "Data Source=|DataDirectory|\\libdb.sdf; Persist Security Info=False ;"; Please try to use absolute path like connectionstring = "Data Source=C:\\Users\\chandra\\Documents\\Visual Studio 2010\\Projects\\Window\\LMS\\AppData\\LMSDatabase.sdf;Persist Security Info=False;"; I hope this will work.

Thanks