Case condition broken need assistance to fix - sql

Question

New to SQL, so please accept my apologies. A query was created that when
If HBL_CLNT_CAT._HS_EB_CODE1 = 'BF' then value = TBM_BILLGRP._HS_EB_DET1
If HBL_CLNT_CAT._HS_EB_CODE2 = 'BF' then value = TBM_BILLGRP._HS_EB_DET2
However of the _HS_EB_DET# exceeds 100 characters add a '*'.
With assistance a query was developed, however it broken the condition rules in that the 'then statement/action would fail because it was greater number than the condition statement (select _hs_eb_code1 from hbl_cat where hs_eb_code = 'bf' that returns only 1 record).
select
case when len(format) > 100
then left(format, 100) + '*'
else format
end as format
from
( select
case when exists ( select _hs_eb_code1
from hbl_cat
where hs_eb_code = 'bf'
)
then tbm_bllgrp._hs_eb_det1
end
) as format
from tbm_bllgrp

Answer 1

Formatting the code would have helped you find the error. Try this:
select
case when len(format) > 100
then left(format, 100) + '*'
else format
end as format
from
( select
case when exists ( select _hs_eb_code1
from hbl_cat
where hs_eb_code = 'bf'
)
then tbm_bllgrp._hs_eb_det1
end as format
from tbm_bllgrp
) as tmp

Answer 2

The above query is broken in several places. A working statement could look like this:
SELECT CASE
WHEN len(x.myval) > 100 THEN
left(x.myval,100) + '*'
ELSE
x.myval
END AS format
FROM (
SELECT CASE
WHEN h.HS_EB_CODE1 = 'BF' THEN
t._HS_EB_DET1
WHEN h._HS_EB_CODE2 = 'BF' THEN
t._HS_EB_DET2
ELSE
'unknown option'
END AS myval
FROM HBL_CLNT_CAT AS h
JOIN TBM_BILLGRP AS t ON ??? -- how are the two tables connected?
WHERE ??? -- some condition or do you want all rows in the table?
) AS x
But you need to tell us first, how TBM_BILLGRP and HBL_CLNT_CAT can be joined, and how you select your rows.
BTW, upper case is pointless in SQL-Server. Identifiers are case-insensitive as long as they are not enclosed in double quotes " " or brackets [ ].