>Hi All -
>
>I have this query defined.
>

select * from TIP_Ledger where FundType='RTA' and isnull(checknumber,'')=''

>
>Interestingly, it produces the records specified and also those where checknumber is blank but not null. This is good but a surprise to me. I was wondering if it can be relied upon or is it just a quirk.
>
>Thanks for your shared knowledge.

Of course you will get blank checknumbers too.
The whole point if ISNULL() function is to convert NULLs to something that isn't null.
if you want to get ONLY NULLs:

select * from TIP_Ledger where FundType='RTA' and checknumber IS NULL