IF function?

On Mon, Apr 30, 2007 at 10:51:36PM -0700, novnov wrote:

Does postgresql have a built in IF function that allows one to eval a
condition and return one or another value? Like:

IIF(mybooleanfield = true, "It's true", "It's not true")

It has CASE, as in

CASE foo WHEN true THEN 'It''s true' ELSE 'It''s not true' END;

Cheers,
D
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phone: +1 415 235 3778 AIM: dfetter666
Skype: davidfetter

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IF ( condition here)
-- to do
ELSE
-- to
END IF

David Fetter wrote:

On Mon, Apr 30, 2007 at 10:51:36PM -0700, novnov wrote:

Does postgresql have a built in IF function that allows one to eval a
condition and return one or another value? Like:

IIF(mybooleanfield = true, "It's true", "It's not true")

It has CASE, as in

CASE foo WHEN true THEN 'It''s true' ELSE 'It''s not true' END;

Cheers,
D
--
David Fetter <david@fetter.org> http://fetter.org/
phone: +1 415 235 3778 AIM: dfetter666
Skype: davidfetter

I didn't express myself clearly. Is there an IIF type function one can use
inline in a view?

SELECT UserName, IIF(mybooleanfield = true, "It's true", "It's not true") as
SayIt FROM tblUser

I don't think there is, and I don't 'need' it, just could be handy once in a
while.

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On 01/05/2007 15:38, novnov wrote:

I didn't express myself clearly. Is there an IIF type function one can use
inline in a view?

SELECT UserName, IIF(mybooleanfield = true, "It's true", "It's not true") as
SayIt FROM tblUser

That's what CASE is for:

select
case
when mybooleanfield then 'It''s true'
else 'It''s not true'
end as SayIt
from
tblUser;

(...or something like that - look it up in the docs).

Ray.

---------------------------------------------------------------
Raymond O'Donnell, Director of Music, Galway Cathedral, Ireland
rod@iol.ie
---------------------------------------------------------------

On May 1, 2007, at 12:57 AM, David Fetter wrote:

On Mon, Apr 30, 2007 at 10:51:36PM -0700, novnov wrote:

Does postgresql have a built in IF function that allows one to eval a
condition and return one or another value? Like:

IIF(mybooleanfield = true, "It's true", "It's not true")

It has CASE, as in

CASE foo WHEN true THEN 'It''s true' ELSE 'It''s not true' END;

Or, for simple binary conditions like that:

CASE WHEN foo is TRUE
THEN "it's true"
ELSE "it's not true"
END

erik jones <erik@myemma.com>
software developer
615-296-0838
emma(r)

On Tue, 2007-05-01 at 07:38 -0700, novnov wrote:

I didn't express myself clearly. Is there an IIF type function one can
use
inline in a view?

SELECT UserName, IIF(mybooleanfield = true, "It's true", "It's not
true") as
SayIt FROM tblUser

I think people understood you. The part that may not be obvious to you
is that case can be used in the select list, as in:
SELECT UserName, CASE mybool WHEN TRUE THEN $$It's true$$ ELSE $$It's
not true$$ END AS veracity FROM sometable;

or even
SELECT UserName, $$It's$$ || CASE mybool WHEN TRUE THEN '' ELSE ' not'
END || ' true' AS veracity FROM sometable;

Nearly anything you can express in a select statement can also be turned
into a view. (The only exception that comes to mind is that select
allows cols with the same name, but views don't.)

If you really want a function, that's not hard to write for the case of
consistent types:
rkh@csb-dev=> create or replace function iif(boolean,text,text)
returns text language sql as 'select case $1 when true then $2
else $3 end';
CREATE FUNCTION
Time: 71.242 ms
rkh@csb-dev=> select iif(true,'yep','nope');
iif
-----
yep
(1 row)

Time: 1.468 ms
rkh@csb-dev=> select iif(false,'yep','nope');
iif
------
nope
(1 row)

rkh@csb-dev=> select $$It's$$ || iif(true,'',' not') || ' true';
?column?
-----------
It's true
(1 row)

The function is NOT declared strict: it can return null on null input. I
think that is the right behavior for the boolean, but not for the return
strings.

-Reece

--
Reece Hart, http://harts.net/reece/, GPG:0x25EC91A0

I see...well, that's excellent. Thanks to all who responded.

Reece Hart wrote:

On Tue, 2007-05-01 at 07:38 -0700, novnov wrote:

I didn't express myself clearly. Is there an IIF type function one can
use
inline in a view?

SELECT UserName, IIF(mybooleanfield = true, "It's true", "It's not
true") as
SayIt FROM tblUser

I think people understood you. The part that may not be obvious to you
is that case can be used in the select list, as in:
SELECT UserName, CASE mybool WHEN TRUE THEN $$It's true$$ ELSE $$It's
not true$$ END AS veracity FROM sometable;

or even
SELECT UserName, $$It's$$ || CASE mybool WHEN TRUE THEN '' ELSE ' not'
END || ' true' AS veracity FROM sometable;

Nearly anything you can express in a select statement can also be turned
into a view. (The only exception that comes to mind is that select
allows cols with the same name, but views don't.)

If you really want a function, that's not hard to write for the case of
consistent types:
rkh@csb-dev=> create or replace function iif(boolean,text,text)
returns text language sql as 'select case $1 when true then $2
else $3 end';
CREATE FUNCTION
Time: 71.242 ms
rkh@csb-dev=> select iif(true,'yep','nope');
iif
-----
yep
(1 row)

Time: 1.468 ms
rkh@csb-dev=> select iif(false,'yep','nope');
iif
------
nope
(1 row)

rkh@csb-dev=> select $$It's$$ || iif(true,'',' not') || ' true';
?column?
-----------
It's true
(1 row)

The function is NOT declared strict: it can return null on null input. I
think that is the right behavior for the boolean, but not for the return
strings.

-Reece

--
Reece Hart, http://harts.net/reece/, GPG:0x25EC91A0

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You must use
CASE var=val2 THEN [true statement] ELSE [false statement] END