Question

‘Discussions’ table schema

title      description    desid    replyto    upvote    downvote   views
browser    used           a1        none        1          1       12
-          bad topic      b2        a1          2          3       14
sql        database       a3        none        4          5       34
-          crome          b4        a3          3          4       12

The above table has two types of content types Main Topics and Comments. Unique content identifier ‘desid’ used to identify that its a main topic or a comment. ‘desid’ starts with ‘a’ for Main Topic and for comment ‘desid’ starts with ‘b’. For comment ‘replyto’ is the ‘desid’ of main topic to which this comment is associated.

I like to find out the list of the top main topics that are arranged on the basis of (upvote+downvote+visits+number of comments to it) addition. The following query gives top topics list in order of (upvote+downvote+visits)

select * with highest number of upvote+downvote+views by query

select * 
from [DB_user1212].[dbo].[discussions] 
where desid like 'a%'
order by (upvote+downvote+visited) desc

For (comments+upvote+downvote+views ) i tried

select *
from [DB_user1212].[dbo].[discussions]
where desid like 'a%'
order by (select count(*)
           from [DB_user1212].[dbo].[discussions]
           where replyto = desid )+upvote+downvote+visited) desc 

but it didn’t work . Because its not possible to send desid from outer query to innner subquery. Please tell me how to solve this. Please note that I want solution in query language only.

Answer 1

You need to use table aliases:

select *
from [DB_user1212].[dbo].[discussions] d1 --alias
where desid like 'a%'
order by (select count(*)
           from [DB_user1212].[dbo].[discussions] d2
           where d2.replyto = d1.desid )+upvote+downvote+visited) desc

Now, in the subquery, you can refer to the outer tables by alias (here, d1). I also added d2, which is not necessary here, but it can be useful to be explicit in subqueries.