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.