how can i insert xml value into SQL table

Hi all,

I have some clarification for the below sql query.

my xml is :

<main>
    <Data>
        <COUNTER>A</COUNTER> 
    </Data>
</main>

my query is :

CREATE TABLE #temp
(
   
    COUNTER VARCHAR(1)
);
 
INSERT #temp
SELECT    
    Data.value('(/COUNTER/text())[1]','VARCHAR(100)') AS COUNTER,

FROM
    @XML.nodes('/main/Data') AS AdviceData (Data);

INSERT INTO SECONDTABLE(COUNTER)
SELECT CASE T.COUNTER WHEN 'A' THEN 1 END AS COUNTER
FROM #temp T

The above query is working fine. but i don't want to use case statement. why because sometimes counter is Z then i should show 26. without case statement how can i achieve this.

thanks in advance