如何在PHP中使用变量的新值？

Why does $validSave always contains FALSE even I click the btnEdit?

Here's the code:

$validSave = false;

if(isset($_POST['btnSearch'])){
   if(isset($_POST['btnEdit']){
     $validSave = true;
   }
}

if(isset($_POST['btnSave']){
     if($validSave){
         ... //Does not go here after I press the btnEdit
     }
     else{
        echo "Unable to save"; //It always goes here
     }
}

$validSave always contains FALSE because if(isset($_POST['btnSearch'])) and if(isset($_POST['btnEdit']) are false.if one condition is true and one condition is false then state will not change of $validSave if you have two button if(isset($_POST['btnSearch'])) and if(isset($_POST['btnEdit']) try to use like this

if(isset($_POST['btnSearch']) || isset($_POST['btnEdit'])){
  $validSave = true;
}

or if you have one button and one field you need to try like that

if(isset($_POST['your button name'])){
   $otherField=$_POST['btnSearch'];
    $validSave = true;
}