如何在查询中具有变量的where子句中使用SQL UNION

Question

I'm trying to retrieve data from two tables using UNION but not works in my case. I'm trying this

    $folq = $db->query("select id as pid,folder,name as catname,name,thumb,pathc from hollywood where id = ".$parentid, database::GET_ROW) UNION ("select id as pid,folder,name as catname,name,thumb,pathc from bollywood where id = ".$parentid, database::GET_ROW);

But not works for me. Please suggest me how to achive that.

Answer 1

You need one string query (not two , and in the second query you don't need alias)

 $folq = $db->query("
  select 
      id as pid
      ,folder
      ,name as catname
      ,name
      ,thumb
      ,pathc 
  from hollywood 
  where id =  ".$parentid . 
  " UNION 
    select 
      id 
      ,folder
      ,name
      ,name
      ,thumb
      ,pathc 
  from bollywood 
  where id = ". $parentid

  , database::GET_ROW);

Answer 2

我认为您的查询中存在语法错误，应该是这样的

 $folq = $db->query("select id as pid,folder,name as catname,name,thumb,pathc from hollywood where id = ".$parentid . " UNION select id as pid,folder,name as catname,name,thumb,pathc from bollywood where id = ".$parentid, database::GET_ROW);

Answer 3

Please use this

        $folq = $this->db->query("
            select id as pid,folder,name as catname,name,thumb,pathc from hollywood where id = $parentid 
        UNION  
            select id as pid,folder,name as catname,name,thumb,pathc from bollywood where id = ".$parentid);

Answer 4

This works :)

         $folq = $db->query("
        select id as pid,folder,name as         catname,name,thumb,pathc from category where id         = $parentid 
           UNION  
            select id as pid,folder,name as         catname,name,thumb,pathc from punjabi where id         = ".$parentid, database::GET_ROW);