Setting a variable in T-SQL from a Query - tsql

Question

So I have this query:
select ens_use_new_models_bit from cfo_transaction
inner join dbo.cfo_trans_entity_rel on te_tr_transaction_id=tr_transaction_id
inner join cfo_tran_quote on tq_tr_transaction_id = tr_transaction_id
left outer join cfo_engine_sponsor on ens_rs_sponsor_id = te_co_re_entity_id
where te_rv_rel_type_id=713 and tq_tran_quote_id = 3
It returns a bit value, which can also be NULL. I hardcoded 3 for testing but in reality another proc passes this value in, but that's not important here.
Now, in a stored proc, I need to set a variable that's declared in the proc:
SET #vRtn = NULL
as the string - either 'VBEngines' or 'WFModels', or keep it NULL if the bit from above returns NULL.
'VBEngines' if the bit is off, 'WFModels' if the bit is on.
Then after that, I need to perform a T-SQL condition on the value, to see if it's NULL or not. How would I do this? I'm so bad with SQL.
Thanks.

Answer 1

Assuming that you don't need the bit value itself stored in a variable as that was just a means to an end then this should do it.
select #vRtn = case ens_use_new_models_bit
when 0 then 'VBEngines'
when 1 then 'WFModels'
end /*Implicit Else NULL case*/
from cfo_transaction ...
In the case 0 rows are returned no assignment is made so #vRtn keeps its initial value,

Answer 2

declare #newmodelsbit bit, #vRtn varchar(10)
select #newmodelsbit = ens_use_new_models_bit from cfo_transaction
inner join dbo.cfo_trans_entity_rel on te_tr_transaction_id=tr_transaction_id
inner join cfo_tran_quote on tq_tr_transaction_id = tr_transaction_id
left outer join cfo_engine_sponsor on ens_rs_sponsor_id = te_co_re_entity_id
where te_rv_rel_type_id=713 and tq_tran_quote_id = 3
if #newmodelsbit is null
begin
set #vRtn = null
end
else
begin
if #newmodelsbit = 1 --bit is on
begin
set #vRtn = 'WFModels'
end
else -- bit is off
begin
set #vRtn = ' VBEngines'
end
end