PHP - Anidar consultas tipo filtros

$_SESSION('option') = $var

if ($POST['nameSelect'] == ''){

   $query = (SELECT * FROM tabla WHERE filtroCheckbox = $variable AND filtroInput = $variable)

}

elseif ($POST['$nameCheckbox'] ==''){

   $query = (SELECT * FROM tabla WHERE filtroSelect = $variable AND filtroInput = $variable)

}

elseif ($POST['$nameInput'] ==''){

   $query = (SELECT * FROM tabla WHERE filtroSelect = $variable AND filtroCheckbox = $variable)

}

else{

   $query = (SELECT * FROM tabla WHERE filtroSelect = $variable AND filtroCheckbox = $variable AND filtroInput = $variable)

}

<form class="mx-3" action=''" onsubmit="myFunction()">

<input type="" name="name" class="form-control" id="name">

<!-- cake php -->

  <?=$this->Form->control('country', ['id' => 'country', 'class' => 'form-control', 'label' => 'País', 'placeholder' => 'PAIS', 'options' => ['' => ''],'onchange'=>"this.form.submit()",'default' => '1]);?>

<!-- cake php -->

</form>

<script type="text/javascript">

  function myFunction(){

    var name = document.getElementById('name');

    console.log('hola2');

    console.log(name.value);

    if(name.value == ''){

      name.remove();

    }

  }

</script>