[development] SQL question.
gordon at heydon.com.au
Fri Feb 3 05:19:02 UTC 2006
On Thu, 2006-02-02 at 23:33 -0500, Pat Collins wrote:
> On Fri, 03 Feb 2006 15:17:39 +1100, Gordon Heydon <gordon at heydon.com.au> wrote :
> > Hi,
> > I have been trying to work out a small sql issue, and I was wondering if
> > someone might be able to help me.
> > Basically I have 2 tables and I was to do a left join and pull out all
> > rows which has a value in the right hand table or doesn't exist.
> > eg.
> > SELECT a.a, a.b, b.a, b.c FROM a LEFT JOIN b ON a.a = b.a WHERE b.c =
> > 'A';
> Your where clause is going to limit you to only rows where b.c = 'A'.
I thought that this was the case.
> > So basically I want it to return.
> > a b a c
> > 1 1 null null
> > 2 2 2 A
> So you will probably want to add 'OR b.a is null' (or however you have the
> lack of value defined) to your WHERE above.
Yes the 'is null' fixed this for me.
Thanks so much.
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