在Php / MySQL中复选框编辑/更新表单

I have multiple checkbox values stored in a single column in my DB ( Example cat,dogs or dogs,cows etc. it is retrieved as $animals and exploded to compare the values.

            $animal_values = explode(",", $animals);
             $cat = "cat";
              $dogs = "dogs";
              $cow = "cow";
              foreach($animal_values as $value) {


                if( $value ==  $cat ){
                  echo '<li>
                  <input type="checkbox" id="cat" checked="checked"  name="animals[]" value="cat" />
                  <label for="cat">Cat</label>
                  </li>';
                }
                if( $value ==  $dogs ){
                  echo '<li>
                  <input type="checkbox" id="dogs" checked="checked"  name="animals[]" value="dogs" />
                  <label for="dogs">dogs</label>
                  </li>';
                }
                if( $value ==  $cow ){
                echo '<li>
                <input type="checkbox" id="cow" checked="checked"  name="animals[]" value="cow" />
                <label for="cow">cow</label>
                </li>';
                }

This way the values that are present shows up as checked checked boxes.

But the thing is I also want to show boxes for whose values are missing as unchecked boxes. How can I achieve this ??

              <?php
              $animal_value = explode(",", $animal);

              echo '<li>
              <input type="checkbox" id="cat"';?> <?php  if (in_array("cat", $animal_value))  {  echo 'checked="checked"';  } ?> <?php echo 'name="animal[]" value="cat" />
              <label for="cat">Cat</label>
              </li>';

              echo '<li>
              <input type="checkbox" id="dog"';?><?php   if (in_array("dog", $animal_value))  {  echo 'checked="checked"';  } ?> <?php echo ' name="animal[]" value="dog" />
              <label for="dog">Dog</label>
              </li>';

              echo '<li>
              <input type="checkbox" id="cow"';?><?php   if (in_array("cow", $animal_value))  {  echo 'checked="checked"';  } ?> <?php echo 'name="animal[]" value="cow" />
              <label for="cow">COW</label>
              </li>';

             ?>

Any suggestions for Improvement or any other approach its welcome.