Re: How to return a default value if no result

OK, we've thought of another possibility, still seems a bodge though:

Select case when exists(Select vat_rate from vatrates where vat_code='1' and
vat_date<='2014-08-01')

Then (Select vat_rate from vatrates where vat_code='1' and
vat_date<='2014-08-01' order by vat_date desc limit 1)

Else (select 0 as vat_rate from vatrates limit 1)

From: pgsql-novice-owner(at)postgresql(dot)org
[mailto:pgsql-novice-owner(at)postgresql(dot)org] On Behalf Of Rob - TEAM Systems
Ltd
Sent: 22 August 2014 12:19
To: pgsql-novice(at)postgresql(dot)org
Subject: [NOVICE] How to return a default value if no result

I want my query to return at least one row with a default result even if
there are no matches in the database.

As a simple example, getting the valid VAT rate for a transaction date and
VAT code:

Select vat_rate from vatrates where vat_code='1' and vat_date<='2014-08-01'
order by vat_date desc limit 1

This is fine as long as there is a match. If there are no matches, I'd like
it to return a default (0) rather than no result.

I could make sure there is always a result by having a UNION with a
hard-coded record, but this doesn't let me order by a field not in the
result.

In this example I could just make sure there is a dummy row in the table
with a very old date and do something like this:

Select vat_rate from vatrates where (vat_code='1' or vat_code='DUMMY') and
vat_date<='2014-08-01' order by vat_date desc limit 1

But it seems like a bodge to me.

Is there a nice way of forcing a default result somehow?

Thanks,

Rob