Msg 512, Level 16, State 1, Line 19 Subquery returned more than 1 value. :   update ActiveParty 
  set rmname = (select  CONCAT(rmname,rmadr1)
				from ActiveParty
				 where RMADR1 like ('%C/O%') or RMADR1 like ('%Attention%') or RMADR1 LIKE '%!%%' escape '!')
  where RMADR1 in (select  RMADR1
					from ActiveParty
						where RMADR1 like ('%C/O%') or RMADR1 like ('%Attention%') or RMADR1 LIKE '%!%%' escape '!');

Anyone can give some solution for this as soon 