How this query works

Question

select ID,(select name from website_pages where id=pageid) as Pages,

(select name from Panes where id=paneid) as Pane,(select name from website_Controls where id=controlid) as Control,

(select requiressession from website_Controls where id=controlid) as RequiresSession from website_panes_controls

where pageid=(select id from website_pages where name='RefillExpParam.aspx') order by paneid,renderorder

 

I have a question regarding that query from where these values are coming which are high lighted .

 

the Tables and their columns are as follows

website_pages

(ID,Name,Description,HasContent,HasPanes)

website_Controls

(ID,Name,Description,REquiresSession)

website_panes_Controls

(ID,PageID,PaneID,ControlID,RenderOrder)