Case when SQL statement into variable - tsql

Question

I need to create a variable for a case when statement on sybase sql. I have this error from my sql client
A SELECT statement that assigns a value to a variable must not be
combined with data-retrieval operations.
What do I need to do to use this variable the right way?
DECLARE #OutputName CHAR(50)
SELECT #OutputName=
(case when (a.M_TRN_TYPE='XSW' or a.M_TRN_TYPE='SWLEG') then 'FXSW'
when (a.M_TRN_TYPE<>'SWLEG' and a.M_TP_DVCS='C') then 'DCS'
when a.M_TRN_TYPE<>'SWLEG' and a.M_TP_DVCS<>'C' and SUBSTRING(c.M_SP_SCHED0,1,2)='+1' then
(case when b.M_DTE_SKIP_1>=a.M_TP_DTEEXP then 'SPOT' else 'OUTR' end)
when a.M_TRN_TYPE<>'SWLEG' and a.M_TP_DVCS<>'C' and SUBSTRING(c.M_SP_SCHED0,1,2)<>'+1' then
(case when b.M_DTE_SKIP_2>=a.M_TP_DTEEXP then 'SPOT' else 'OUTR' end)
end),
case when #OutputName='XSW' and
(case when c.M_DATESKIP='+1OD' then b.M_DTE_SKIP_1 else b.M_DTE_SKIP_2 end)=a.M_TP_DTEFST
then 0
else a.M_NB
end as 'NBI'
from TP_COMPL_PL_REP b
join TP_ALL_REP a on (a.M_NB=b.M_NB and a.M_REF_DATA=b.M_REF_DATA)
left join DM_SPOT_CONTRACT_REP c on (a.M_NB=c.M_NB and a.M_REF_DATA=c.M_REF_DATA)

Answer 1

The problem is that you can't combine a SELECT which sets a variable with a SELECT which returns data on the screen.
You set #OutputName to (case when (a.M_TRN_TYPE='XSW' .. ) but in the same SELECT you're also trying to display the results of:
case
when #OutputName='XSW' and
(case
when c.M_DATESKIP='+1OD'
then b.M_DTE_SKIP_1
else b.M_DTE_SKIP_2
end)=a.M_TP_DTEFST
then 0
else a.M_NB
end as 'NBI'
You can't have these two in the same SELECT, in the format you're using. My recommendation is to split them, one for assigning the variable:
DECLARE #OutputName CHAR(50)
SELECT #OutputName=
(case when (a.M_TRN_TYPE='XSW' or a.M_TRN_TYPE='SWLEG') then 'FXSW'
when (a.M_TRN_TYPE<>'SWLEG' and a.M_TP_DVCS='C') then 'DCS'
when a.M_TRN_TYPE<>'SWLEG' and a.M_TP_DVCS<>'C' and SUBSTRING(c.M_SP_SCHED0,1,2)='+1' then
(case when b.M_DTE_SKIP_1>=a.M_TP_DTEEXP then 'SPOT' else 'OUTR' end)
when a.M_TRN_TYPE<>'SWLEG' and a.M_TP_DVCS<>'C' and SUBSTRING(c.M_SP_SCHED0,1,2)<>'+1' then
(case when b.M_DTE_SKIP_2>=a.M_TP_DTEEXP then 'SPOT' else 'OUTR' end)
end)
from TP_COMPL_PL_REP b
join TP_ALL_REP a on (a.M_NB=b.M_NB and a.M_REF_DATA=b.M_REF_DATA)
left join DM_SPOT_CONTRACT_REP c on (a.M_NB=c.M_NB and a.M_REF_DATA=c.M_REF_DATA)
and one for returning the data:
SELECT case when #OutputName='XSW' and
(case when c.M_DATESKIP='+1OD' then b.M_DTE_SKIP_1 else b.M_DTE_SKIP_2 end)=a.M_TP_DTEFST
then 0
else a.M_NB
end as 'NBI'
from TP_COMPL_PL_REP b
join TP_ALL_REP a on (a.M_NB=b.M_NB and a.M_REF_DATA=b.M_REF_DATA)
left join DM_SPOT_CONTRACT_REP c on (a.M_NB=c.M_NB and a.M_REF_DATA=c.M_REF_DATA)