create dummy column in a query that its value come from a condition

am preparing a query which i will use it in Crystal Report the query is working fine so far but I want to add one more column (dummy column) which will be filled based on a condition , this is the query :

select AcctCode, AcctName,Segment_0 + '-'+ Segment_1 as Acctnum,max(refdate) ,min(refdate),sum(debit) as Debit,sum(credit)as Credit from oact t0 inner join jdt1 t1 on t0.acctcode = t1.Account
where (Segment_0 LIKE '01%' or segment_0 like '02%'  or Segment_0 like '03%') and ( t0.Segment_1 = '01') and  (refdate  between '2014-01-31' and '2015-12-27' )
group by AcctCode, AcctName,Segment_0, Segment_1
order by  AcctCode 

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if Segment_0 is start with '01' then the value in the dummy column will show 'A' if Segment_0 is start with '02' then the value in the dummy column will show 'L' if Segment_0 is start with '03' then the value in the dummy column will show 'E' i tried to use if statement, and case but luck wasn't in my side :(