$SearchPage->bindParam("il", "".(isset($_GET['book'])?implode(","$_GET['book']):"") ."", "-1"); //WAQB_Param1
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it shows some error and I think it should be like as below;
$SearchPage->bindParam("il", "".(isset($_GET['book'])?implode(",",$_GET['book']):"") ."", "-1"); //WAQB_Param1
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Meanwhile just little more help needed to echo back the checked status that means shows back which books I was selected for the query on below code
<input name="book[]" type="checkbox" class="form-check-input" value="<?php echo($booksList->getColumnVal("BookID")); ?>"><?php echo($booksList->getColumnVal("BookNameBD")); ?>