电子邮件验证PHP中的一个条件和多个else语句

Question

I will try to put email validation with have more than one case. First(if):email is required. Second(if): invalid format of email. Third(else): Email is exist(Active User) Fourth(else): Email is in approve(Admin is not approved account yet so its still in request table) Fifth(else):Everything goes well,post the data into database.

I try to solve this by if-else statement but in last two case I do not have any condition its just have to pass that validation.I also try switch statement, but it's not go after the first case:

Here is my validation:

   if(empty($_POST['email']))
     {
         $email=$_POST['email'];
         $emailError="Email is required";
         $error=true;
     }
   else
     {
          $email=$_POST['email'];
          if(!filter_var($email, FILTER_VALIDATE_EMAIL)) 
          {
            $emailError = "Invalid email format";
            $error=true;
          }
          else
              {
                 $sql="SELECT * FROM user WHERE email='$email'";
                 $res=mysqli_query($db,$sql);
                 if (mysqli_num_rows($res) > 0)
                 {
                  $emailError = "Email already exists";
                  $error=true;
                 }
               }

         else 
           {
             $sl="SELECT * FROM request WHERE email='$email'";
             $ress=mysqli_query($db,$sl);
             if (mysqli_num_rows($ress) > 0)
             {
              $emailError = "Your Accout is in process";
              $error=true;
             }
           }
      }   

Answer 1

ok I put the condition for $error & now its working fine. remember that you have to put $exist=""; in starting. here is my code:

   if(empty($_POST['email']))
   {
    $email=$_POST['email'];
    $emailError="Email is required";
    $error=true;
   }
   else {
          $email=$_POST['email'];
          if(!filter_var($email, FILTER_VALIDATE_EMAIL))
         {
           $emailError = "Invalid email format";
           $error=true;
         }
         else
             {
                $sql="SELECT * FROM user WHERE email='$email'";
                $res=mysqli_query($db,$sql);
                if (mysqli_num_rows($res) > 0)
                {
                 $emailError = "Email already exists";
                 $error=true;
                 $exist=1;
                }
            }
            if($exist!=1)
            {
              $sl="SELECT * FROM request WHERE email='$email'";
              $ress=mysqli_query($db,$sl);
              if (mysqli_num_rows($ress) > 0)
              {
               $emailError = "Your Accout is in process";
               $error=true;
              }
            }

        }