sql - Find the user with the most contact -

Users send messages in each other message box, find a user, which most other users know (get and Send ??)

USER_ID

USER_GROUP

MESSAGE_ID

/ li>

MESSAGE_MESSAGE

MESSAGE_FROM_USER

M_ESSAGE_TO_USER

A user can send and receive, so who knows other users (Send and receive by ??) < / P>

Using SQL Server 2005+, CTE:

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  As with usr_list (SELECT x.user_id, select x.message_from_user as tab x union for other user y.user_id, y.message_to_user as other_user tab Y) SELECT TOP 1 ul.user_id, COUNT ( *) AS Un-CTE's equivalent: num_friends as  
 
  SELECT TOP 1 ul.user_id, COUNT (node ​​CTE equivalent:  
 
 *) FROM (SELECT x.user_id, x.message_from_user as other_user from table x UNION SELECT y.user_id, y.message_to_user as other_user table) and UL by UL Group Num_friends DESC  

by User_id ORDER