You got the per-site query from Cai, let me add the network-wide query.
-- result table, don't rename and keep the site column
create table #results ( site nvarchar(250)
, displayname nvarchar(40)
, qcount int
, accountid int);
declare @sql nvarchar(max) = '' -- holds build up sql string
-- build one biq union sql, for each db
select @sql = @sql
+ iif( len(@sql) > 1
, 'union'
, 'insert into #results'
) +
-- here goes the per site query, fully qualify the database objects
N'
select ''' + name + '''
, u.displayname
, count(*)
, u.accountid
from ' + quotename(name) + '.dbo.posts p
inner join ' + quotename(name) + '.dbo.users u on u.id = p.owneruserid
where posttypeid = 1 -- Q
group by u.displayname
, u.accountid
'
from sys.databases
where database_id > 5
-- and (name not like '%.Meta' or name = 'StackExchange.Meta')
--print @sql
-- execute it
exec (@sql)
-- show results
select
'http'https://stackexchange.com/users/'
+ cast(accountid as nvarchar)
+'?tab=top|' + max(displayname) as [network user]
-- rest of columns
, sum(qcount) as [# questions network wide]
from #results
group by accountid
order by sum(qcount) desc
drop table #results
When run today the result looks like this: