hi can any one tell me how can i bulky fy this trugger

when am inserting the opportunity through dat aloader am geeting error list has more than one row for assigne ment

this is my code

trigger Populating_CCY_Pair  on Opportunity (after insert,after update) {
List<opportunity> op=new List<opportunity>();
List<opportunity> opp=new List<opportunity>();
Set<id> accIds = new Set<Id>();
set<string> uniquerecords=new Set<string>();
string ccy_pair;
set<string> uniuqvalues=new set<String>();
op=[select id,name,Bought_CCY__c,CCY_Pair__c,Sold_CCY__c,accountid from opportunity where id=:trigger.new];

for(opportunity o:op)
{
if(o.accountid != null)
        {
            accIds.add(o.accountid);
        }
}
Account ac=[select id,name,CCY_Pairs_Traded__c from account where id=:accIds];
opp=[select id,name,Bought_CCY__c,CCY_Pair__c,Sold_CCY__c,accountid  from opportunity where accountid=:accIds];
ccy_pair='';
try{
for(Opportunity o1:opp)
{
if(!uniuqvalues.contains(o1.CCY_Pair__c.toUpperCase().trim()))
{
uniuqvalues.add(o1.CCY_Pair__c.toUpperCase().trim());
ccy_pair=ccy_pair+o1.CCY_Pair__c+';';
system.debug('uniuqvalues of valuews'+ccy_pair);
}

}
}catch(Exception e){system.debug('@@@'+e);}
//ac.CCY_Pairs_Traded__c=uniquerecords;
ac.CCY_Pairs_Traded__c=ccy_pair.toUpperCase().trim();

system.debug('account updated fields'+ac.CCY_Pairs_Traded__c);
update ac;
system.debug('account updated records'+ac);

}

am getting error an this line

Account ac=[select id,name,CCY_Pairs_Traded__c from account where id=:accIds];