title: After changing the Table Sign-up is not working, why?
body: <p>After changing the table when I signup it gives errors like I didn't type anything. "username required". This is the code for the username it used to work properly before.</p>
  
  <pre><code>if(empty(trim($_POST["Username"]))){
          $Username_err = "Please enter a username.";
      } else{
          // Prepare a select statement
          $sql = "SELECT id FROM users WHERE Username = ?";
  
          if($stmt = mysqli_prepare($link, $sql)){
              // Bind variables to the prepared statement as parameters
              mysqli_stmt_bind_param($stmt, "s", $param_Username);
  
              // Set parameters
              $param_Username = trim($_POST["Username"]);
  
              // Attempt to execute the prepared statement
              if(mysqli_stmt_execute($stmt)){
                  // store result 
                  mysqli_stmt_store_result($stmt);
  
                  if(mysqli_stmt_num_rows($stmt) == 1){
                      $Username_err = "This username is already taken.";
                  } else{
                      $Username = trim($_POST["Username"]);
                  }
              } else{
                  echo "Oops! Something went wrong. Please try again later.";
              }
          }         
          // Close statement
          mysqli_stmt_close($stmt);
      }
  </code></pre>
  
  <p>I dropped the previous table just to learn more and I added a new one with the same name.</p>
  
  <pre><code>CREATE TABLE IF NOT EXISTS users (
  ID INT(8) NOT NULL AUTO_INCREMENT,
  FirstName varchar(255),
  LastName varchar(255),
  Text varchar(255),
  Country varchar(255),
  City varchar(255),
  Email varchar(255),
  Mobile BIGINT(20),
  Username varchar(255),
  Password varchar(255),
  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
  CONSTRAINT UC_users UNIQUE (ID)
  );
  </code></pre>
  
  <p>This is the table now, what am I missing? </p>