例子：

namespace login

{

public partial class loginForm : Form

{

public loginForm()

{

InitializeComponent();

}

private void button1_Click(object sender, EventArgs e)

{

SqlConnection conn = null;

try

{

string connstring = "data source=.;initial catalog =MyQQ;integrated security=true";

conn = new SqlConnection(connstring);

conn.open();

string selectstring = "select Count(MyQQID) from MyQQInfo where MyQQID= " + txtID.Text.Trim() + "and Password=" + txtPSW.Text.Trim();

cmd.Connection = conn;

SqlCommand cmd = new SqlCommand(selectstring,conn);

int i = int.Parse(cmd.ExecuteScalar().ToString());

if(i == 1)

{

MessageBox.Show("登入成功");

Insert i = new Insert();

i.Show();

}

else

{

MessageBox.Show("登入失敗");

}

}

catch (SqlException ex)

{

throw ex;

}

finally

{

conn.close();

}

}

}