如何检查，这是利用或在SQL表中的值

private void txtCourseName_Leave(object sender, EventArgs e)

        {

            SqlCon = DBCon.DBOpenConnection();

            Query = "Select distinct Name from tblDepartmentMaster";

            SqlCmd = new SqlCommand(Query, SqlCon);

            SqlDr = SqlCmd.ExecuteReader();

            while (SqlDr.Read())

            {

                txtName.Text = SqlDr.GetString(0).ToString();

            }

            MessageBox.Show("Already Exist the Name!", "Already Exist", MessageBoxButtons.OK, MessageBoxIcon.Information);

            txtCourseName.Clear();

            ActiveControl = txtCourseName;

 

            SqlDr.Close();

 

        }

DataSet ds = new DataSet();

            SqlDataAdapter ad = new SqlDataAdapter("select * from technicalregistration where strloginname='" + txtusername.Text + "' and strloginpwd='" + txtpassword.Text + "'", sqlcon);

            ad.Fill(ds);

            if (ds.Tables[0].Rows.Count > 0)

            {

                Response.Redirect("Somepage.aspx");

            }

            else

                lblmessage.Text = "Invalid UserName and Password";

 

            txtusername.Text = "";

            txtpassword.Text = "";