Filling data in textboxes on textchange

private void txtRegNo_TextChanged(object sender, EventArgs e)
        {
            string slctCmdEmpId = "SELECT Emp_Id FROM EMPLOYEE WHERE Emp_RegNo='" + txtRegNo.Text + "' and Loc_Id = '" + Program.locId + "'";
            int empId = qc.DataReadInt(slctCmdEmpId);

            string slctCmdData = "SELECT * FROM EMPLOYEE WHERE Emp_Id='" + empId + "' AND Emp_RegNo='" + txtRegNo.Text + "' and Loc_Id = '" + Program.locId + "'";
            SqlDataReader sdr = (null);
            sdr = qc.readData(slctCmdData);
            sdr.Read();
            txtEmpName.Text = sdr["Emp_Name"].ToString();
            txtFatherName.Text = sdr["Emp_FatherName"].ToString();
            txtCNIC.Text = sdr["Emp_CNIC"].ToString();
            cmbGender.Text = sdr["Emp_Gender"].ToString();
            txtPhone.Text = sdr["Emp_Phone"].ToString();
            cmbStatus.Text = sdr["Emp_Status"].ToString();
            cmbDesignation.Text = sdr["Emp_Designation"].ToString();
            txtEmail.Text = sdr["Emp_Email"].ToString();
            rchAddress.Text = sdr["Emp_Address"].ToString();
            rchDetails.Text = sdr["Emp_Details"].ToString();
            txtUserId.Text = sdr["Emp_RegNo"].ToString();
            dtEmpReg.Value = Convert.ToDateTime(sdr["Emp_RegDate"]);
        }