สอบถามเรื่องการ Query ข้อมูลโดยใช้ Select ... And ครับ

if($_POST["date1"] != "" || $_POST["date2"] != "" || $_POST["cpn1"] != "" || $_POST["cpn2"] != "" )
		{
		$strSQL  = "SELECT * FROM w_inkput ";
		$strSQL .= "INNER JOIN v_printer ON v_printer.pn_id = w_inkput.pu_pid ";
		$strSQL .= "LEFT JOIN z_department ON z_department.dpt_id = v_printer.pn_dpt_id ";
		$strSQL .= "LEFT JOIN z_company ON z_company.cpn_id = z_department.cpn_id ";
		$strSQL .= "WHERE 1 ";
	
if($_POST["date1"] != "")
			{
			$strSQL .= " AND w_inkput.pu_datep BETWEEN '".$_POST["date1"]."' AND '".$_POST["date2"]."'";
			}
if($_POST["cpn1"] != "")
			{
			$strSQL .= " AND z_company.cpn_id = '".$_POST["cpn1"]."'";  
			}
			
if($_POST["cpn2"] != "")
			{
			$strSQL .= " AND z_company.cpn_id = '".$_POST["cpn2"]."'";  
			}