Re: dumb question

2016-06-02 14:23 GMT-03:00 Steve Crawford <scrawford(at)pinpointresearch(dot)com>:

> Something like:
>
> select max(id) from yourtable where sts=0 and ref_id is null;
>
> That assumes that ref_id is null. It would help to see your table
> structure and the query you tried that doesn't work. If ref_id is actually
> a character string then you might need ref_id='' or coalesce(ref_id,'')=''
> if it can be null or empty string.
>
> Cheers,
> Steve
>
>
> On Thu, Jun 2, 2016 at 10:16 AM, Steve Clark <steve(dot)clark(at)netwolves(dot)com>
> wrote:
>
>> Hi List,
>>
>> I am a noob trying to do something that seems like it should be easy but
>> I can't figure it out.
>>
>> I have a table like so:
>>
>> id | ref_id | sts
>> ------------------
>> 1 | | 0
>> 2 | 1 | 1
>> 3 | | 0
>> 4 | | 0
>> 5 | 4 | 1
>> 6 | | 0
>> 7 | 6 | 1
>>
>> I want to find the max(id) whose sts is 0 but whose id is not referenced
>> by ref_id.
>>
>> so the answer would be id=3.
>>
>> Thanks for any pointers,
>> Steve
>>
>> --
>>
>>
>>
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>
>

I think sts=0 means ref_id is null

So, what I think he wants to achieve is:

select max(id) from yourtable where sts=0 and id not in (select ref_id from
yourtable);

Isn't it?