mysql_num_rows（）期望参数1在android [duplicate]处是资源错误

Question

This question already has an answer here:

• mysql_num_rows() expects parameter 1 to be resource, boolean given in [duplicate] 2 answers

I am trying to send userid and otp which is entered in an edittext in an android app but from server side i get following response.

mysql_num_rows() expects parameter 1 to be resource, boolean given in /nfs/c07/h02/mnt/111018/domains/surun.co/html/demo/rest/api.php on line 168

line no 168 from php code

if(mysql_num_rows($results) > 0)

The php code in more details follows:

 public function selectQuery($table_name,$fields,$where="",$show = 0)

    {

       $i =0;

       if($where == "")

       $sql = "SELECT  ".$fields." FROM ".$table_name;

       else

       $sql = "SELECT  ".$fields." FROM ".$table_name." WHERE ".$where;

      //MySqli Select Query

      if($show == 1)

      return $sql;

      $results = mysql_query( $sql,$this->db );

      if(mysql_num_rows($results) > 0)

      {

        while($row = mysql_fetch_assoc($results))

        {

          $result[$i++]= $row;

        }

      }

      return $result;

    }

</div>

Answer 1

Read this link and apply these changes How could I change this mysql to mysqli? while also adding error checking in the form of

 $results = mysqli_query($this->db, $sql) or die (mysqli_error($connection));

(or for MySQL just use $results = mysqli_query($sql,$this->db) or die (mysql_error()); )

What you currently have is that your $this->db value is not connecting the database properly or you have a syntax error in your WHERE clause.