Thread: RE: [SQL] Please help: How to determine largest of two numbers in a query?

Thank you for the advice..

Ideally I would like to write a function, but I am just learning Postgres
and not familiar with creating functions like "greatest_int".

In this case, the two values represent to different data streams. For the
information I need, I only need the greatest of the two.

To work around this, I've started using two separate SELECT statements with
the comparison as part of the WHERE command. I also just tried the SELECT ..
UNION SELECT .. command, and it appears to have worked.

Thanks,
Greg

-----Original Message-----
From: David Hartwig [mailto:daybee@bellatlantic.net]
Sent: Wednesday, December 02, 1998 8:25 PM
To: Greg Youngblood
Cc: 'PostgreSQL SQL List'
Subject: Re: [SQL] Please help: How to determine largest of two numbers
in a query?


My $.03 worth, without really knowing what these values represent:

There is no such "standard" query that can conditionally select between two
columns.   Fortunately PostgreSQL will allow you to create function - of one
does not already exist.

The function would be something like:
    greater_int(integer a, integer b)
It takes two integers arguments and returns the greater integer.

Then you do something like:

CREATE VIEW  myview AS
    SELECT yyymmdd, key, greater_int(value1, value2) FROM mytable;

Or just do the SELECTs directly.

This may not be the most efficient way to accomplish your goal.   I would
also
take a good look at may table design.   Value1 and value2 MAY be a repeating
group and you may want to normalize a little more.  Or not.