ถามวิธีแปลงข้อมูลจาก string เป็น arrray ใส่ select multipleหน่อยครับ

<div class="row">
								<br>
								<br>
								<label class="control-label">Param2</label>
									<?php
										$sqls="SELECT param2  
										FROM data_entry1,attribute_map,operation_map 
										WHERE data_entry1.operation=operation_map.operation and 
										data_entry1.attribute_code=attribute_map.attribute_code and 
										param1 in ('st_validate_partno_with_bom','st_validate_IQR_with_bom_by_serialno') and data_entry1.attribute_Code=". $strattributeID  ;
										$dbquery1 =sqlsrv_query($conn,$sqls);
									?>
									<?php
											while($rws = sqlsrv_fetch_array($dbquery1)){
												$myArray = explode(',', $rws["param2"]);
												print_r($myArray);
												?>
									<select multiple class="form-control s-multiple" style="width: 450px; height: 350px; "  id="PresenterList" name="txtparam2[]">
											<option value="<?=$rws['param2']?>"><?=$rws['param2']?></option>
											<?php
											}?>
									</select>
						</div>