How to show numbers of datasets C#

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Hello I want to show the number of datasets after klicking a button. But if i click the Button the Program crashes. The error message is: The ConnectionString property was not initialized

My code:

private void button2_Click_1(object sender, EventArgs e)
        {
            this.timer1.Start();

            SqlCeConnection conn;
            SqlCeCommand cmd;
            SqlCeDataReader rdr;
                
                conn = new SqlCeConnection();
                cmd = new SqlCeCommand("SELECT COUNT(*) FROM Pigeons", conn);
                conn.Open();
                MessageBox.Show(cmd.ExecuteScalar().ToString());

What I have tried:

I looked up in the internet but I couldn't find any solution.

Posted 19-Jul-18 22:26pm

Member 13917889

Updated 19-Jul-18 22:41pm

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OriginalGriff · Accepted Answer · 2018-07-19T22:42:00

Well, yes - it will. Look at the code:

conn = new SqlCeConnection();
cmd = new SqlCeCommand("SELECT COUNT(*) FROM Pigeons", conn);
conn.Open();

You have created a connection object, but you don't tell it what you want it to connect to! SqlCE is a file-based database: you have to at the very minimum specify the file you want to use and provide that info to your SqlCEConnection instance.
SQL Server Compact connection strings - ConnectionStrings.com[^]

string strConnect = @"Data Source=MyFolder\MyData.sdf;Persist Security Info=False;";
conn = new SqlCeConnection(strConnect);
cmd = new SqlCeCommand("SELECT COUNT(*) FROM Pigeons", conn);
conn.Open();