Re: dumb question

This is your request, translated directly into SQL

	select max(id) from sometable where sts=0 and ref_id IS NULL

Looking at your sample, it seems that sts is always 1 when ref_id exists, so it may possibly simplify to:

	select max(id) from sometable where sts=0

-----Original Message-----
From: pgsql-general-owner@postgresql.org [mailto:pgsql-general-owner@postgresql.org] On Behalf Of Steve Clark
Sent: Thursday, June 2, 2016 9:56 AM
To: pgsql 
Subject: [GENERAL] dumb question

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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