how to retrieve custom categories and post and author in wordpress

Hello my developers please include this class and call your function according to your requirement
<?php

class common_class {


public function  mainCagoryId(){
$parent = 0;
    $sql_query = "SELECT
   wt.term_id
FROM
wp_terms wt
INNER JOIN
wp_term_taxonomy wtt
ON

wt.term_id = wtt.term_id
WHERE
wtt.taxonomy = 'category' AND
wtt.parent = '".$parent."' AND
wt.name!= 'Uncategorized' order by RAND() limit 1

";

        $rs = @mysql_query($sql_query);
      $res=mysql_fetch_array($rs);
 return $res['term_id'];
}
 public function mainCategory()

 {
    $catArr = array();
$parent = 0;
    $sql_query = "SELECT
   wt.term_id, wt.name, wt.slug,
wtt.term_taxonomy_id, wtt.taxonomy, wtt.description, wtt.parent, wtt.count
FROM
wp_terms wt
INNER JOIN
wp_term_taxonomy wtt
ON

wt.term_id = wtt.term_id
WHERE
wtt.taxonomy = 'category' AND
wtt.parent = '".$parent."' AND
wt.name!= 'Uncategorized' order by wt.sort_item ASC

";

        $rs = @mysql_query($sql_query);
      if($rs && @mysql_num_rows($rs)>0)
     {
      $i=1;
      while($row = @mysql_fetch_array($rs))
      {

                     $catArr['term_id'][$i]           =        $row['term_id'];
 $catArr['name'][$i]              =        $row['name'];
 $catArr['slug'][$i]              =        $row['slug'];
 $catArr['term_taxonomy_id'][$i]  =        $row['term_taxonomy_id'];
 $catArr['taxonomy'][$i]          =        $row['taxonomy'];
 $catArr['description'][$i]       =        $row['description'];
                 
     $i=$i+1;

                 }
    }

return $catArr;
  }


      function getBook($catid)
   {
  $categoryId = $catid;
  $productArr= array();


  $sql_query = "SELECT
wp.ID, wp.post_title, wp.post_content, wp.guid, wp.post_name
FROM
wp_term_relationships wtr
INNER JOIN
wp_posts wp
ON
wtr.object_id = wp.ID



WHERE
wtr.term_taxonomy_id = '".$categoryId."' AND
wp.post_status != 'trash' order by wp.post_title asc
";


$rs = @mysql_query($sql_query);
if($rs && @mysql_num_rows($rs)>0)
{
   $i=1;
while($row = @mysql_fetch_array($rs))
      {

                     $productArr['ID'][$i]                =        $row['ID'];
 $productArr['post_title'][$i]        =        $row['post_title'];
 $productArr['post_content'][$i]      =        $row['post_content'];
 $productArr['post_name'][$i]         =        $row['post_name'];
               
     $i=$i+1;
                 }

     }
     
   return $productArr;

  }


   function getBookLimit($catid)
   {

   $categoryId = $catid;

 $productArr= array();




   $sql_query = "SELECT
distinct wp.ID, wp.post_title, wp.post_content, wp.guid, wp.post_name
FROM
wp_term_relationships wtr
INNER JOIN
wp_posts wp
ON
wtr.object_id = wp.ID



WHERE
wtr.term_taxonomy_id = '".$categoryId."' AND
wp.post_status != 'trash' order by wp.post_title asc limit 0,5

";
$rs = @mysql_query($sql_query);
if($rs && @mysql_num_rows($rs)>0)
{
   $i=1;
while($row = @mysql_fetch_array($rs))
      {

                     $productArr['ID'][$i]                =        $row['ID'];
 $productArr['post_title'][$i]        =        $row['post_title'];
 $productArr['post_content'][$i]      =        $row['post_content'];
 $productArr['post_name'][$i]         =        $row['post_name'];
               
     $i=$i+1;
                 }

     }
     
   return $productArr;

  }








  public function bestSellerCategory()

 {
       $bestSellerArr = array();
    $parent = 0;
      $sql_query = "SELECT
   wt.term_id, wt.name, wt.slug,
wtt.term_taxonomy_id, wtt.taxonomy, wtt.description, wtt.parent, wtt.count
FROM
wp_terms wt
INNER JOIN
wp_term_taxonomy wtt
ON

wt.term_id = wtt.term_id
WHERE
wtt.taxonomy = 'category' AND
wtt.parent = '".$parent."' AND
wt.name!= 'Uncategorized' order by RAND()

";
        $rs = @mysql_query($sql_query);
      if($rs && @mysql_num_rows($rs)>0)
     {
      $i=1;
      while($row = @mysql_fetch_array($rs))
      {

                     $bestSellerArr['term_id'][$i]           =        $row['term_id'];
 $bestSellerArr['name'][$i]              =        $row['name'];
 $bestSellerArr['slug'][$i]              =        $row['slug'];
 $bestSellerArr['term_taxonomy_id'][$i]  =        $row['term_taxonomy_id'];
 $bestSellerArr['taxonomy'][$i]          =        $row['taxonomy'];
 $bestSellerArr['description'][$i]       =        $row['description'];
                 
     $i=$i+1;

                 }
    }
return $bestSellerArr;
  }


     function bestSellerBook($catid)
   {

  $categoryId = $catid;

  $productArr= array();




  $sql_query = "SELECT
wp.ID, wp.post_title, wp.post_content, wp.guid, wp.post_name
FROM
wp_term_relationships wtr
INNER JOIN
wp_posts wp
ON
wtr.object_id = wp.ID



WHERE
wtr.term_taxonomy_id = '".$categoryId."' AND
wp.post_status != 'trash' order by wp.post_date_gmt desc limit 0,2

";
$rs = @mysql_query($sql_query);
if($rs && @mysql_num_rows($rs)>0)
{
   $i=1;
while($row = @mysql_fetch_array($rs))
      {

                     $productArr['ID'][$i]                =        $row['ID'];
 $productArr['post_title'][$i]        =        $row['post_title'];
 $productArr['post_content'][$i]      =        $row['post_content'];
 $productArr['post_name'][$i]         =        $row['post_name'];
               
     $i=$i+1;
                 }

     }
       

    return $productArr;

  }



   public function get_bookdetails($id)

 {
 
   $bookDetailsArr = array();
     $sql_query = "SELECT
   ID,post_content,post_title,guid
FROM
wp_posts



WHERE
ID  = '".$id."'

";
        $rs = @mysql_query($sql_query);
        if($rs && @mysql_num_rows($rs)>0)
       {
   
      while($row = @mysql_fetch_array($rs))
      {
                      $bookDetailsArr[1]       =        $row['ID'];
  $bookDetailsArr[2]       =        $row['post_title'];
  $bookDetailsArr[3]       =        $row['post_content'];
  $bookDetailsArr[4]       =        $row['guid'];
     }
    }

return $bookDetailsArr;
     }



public function get_category($catid)

 {
 
  $catArrr = array();
     $sql_query = "SELECT
   wt.term_id, wt.name,wtt.description,wtt.term_taxonomy_id
FROM
wp_terms wt
INNER JOIN
wp_term_taxonomy wtt
ON

wt.term_id = wtt.term_id
WHERE
wt.term_id = '".$catid."' AND wtt.taxonomy = 'category' and wt.name!= 'Uncategorized'  
";


        $rs = @mysql_query($sql_query);
        if($rs && @mysql_num_rows($rs)>0)
       {
   
      while($row = @mysql_fetch_array($rs))
      {
                      $catArrr[1]       =        $row['term_id'];
  $catArrr[2]       =        $row['name'];
  $catArrr[3]       =        $row['description'];
  $catArrr[4]       =        $row['term_taxonomy_id'];      

     }
    }

return $catArrr;
     }


  public function get_authorName($id)

        {
 
    $authorname = array();
      $sql_query = " SELECT
                    post_id , MAX( IF( meta_key = 'author_name', meta_value , NULL ) ) AS author
         
             FROM
                                wp_postmeta

                          WHERE post_id =".$id."
";
        $rs = @mysql_query($sql_query);
        if($rs && @mysql_num_rows($rs)>0)
       {
   
      while($row = @mysql_fetch_array($rs))
      {
                      $authorname[1]               =        $row['post_id'];
  $authorname[2]               =        $row['author'];

     }
    }

return $authorname;
     }



 public function get_pdfurl($id)

        {
 
    $pdfurl = array();
       $sql_query = " SELECT
                    post_id , MAX( IF( meta_key = 'pdf_url', meta_value , NULL ) ) AS PDFURL
       
         
             FROM
                                wp_postmeta

                          WHERE post_id =".$id."
";
        $rs = @mysql_query($sql_query);
        if($rs && @mysql_num_rows($rs)>0)
       {
   
      while($row = @mysql_fetch_array($rs))
      {
                      $pdfurl[1]               =        $row['post_id'];
  $pdfurl[2]               =        $row['PDFURL'];

     }
    }

return $pdfurl;
     }


function popularbook($catid)
   {

 $categoryId = $catid;

 $productArr= array();




  $sql_query = "SELECT
wp.ID, wp.post_title, wp.post_content, wp.guid, wp.post_name
FROM
wp_term_relationships wtr
INNER JOIN
wp_posts wp
ON
wtr.object_id = wp.ID



WHERE
wtr.term_taxonomy_id = '".$categoryId."' AND
wp.post_status != 'trash' order by wp.ID desc limit 0,20

";
$rs = @mysql_query($sql_query);
if($rs && @mysql_num_rows($rs)>0)
{
   $i=1;
while($row = @mysql_fetch_array($rs))
      {

                     $productArr['ID'][$i]                =        $row['ID'];
 $productArr['post_title'][$i]        =        $row['post_title'];
 $productArr['post_content'][$i]      =        $row['post_content'];
 $productArr['post_name'][$i]         =        $row['post_name'];                
     $i=$i+1;
                 }

     }
     
   return $productArr;

  }

function allCategorypopularbook($catid)
{

 $categoryId = $catid;

 $productArr= array();

  $sql_query = "SELECT
wp.ID, wp.post_title, wp.post_content, wp.guid, wp.post_name
FROM
wp_term_relationships wtr
INNER JOIN
wp_posts wp
ON
wtr.object_id = wp.ID



WHERE
wtr.term_taxonomy_id = '".$categoryId."' AND
wp.post_status != 'trash' order by wp.ID desc limit 0,5

";
$rs = @mysql_query($sql_query);
if($rs && @mysql_num_rows($rs)>0)
{
   $i=1;
while($row = @mysql_fetch_array($rs))
      {

                     $productArr['ID'][$i]                =        $row['ID'];
 $productArr['post_title'][$i]        =        $row['post_title'];
 $productArr['post_content'][$i]      =        $row['post_content'];
 $productArr['post_name'][$i]         =        $row['post_name'];
               
     $i=$i+1;
                 }

     }
     
   return $productArr;

  }












}
?>