MS SQL "isDate" equivalent in plpgsql?

Daniel Gehrke wrote:

I am porting from MS SQL 7.0 to PostgreSQL. In one Stored Procedure the
function "isDate" is used. IsDate determines, whether the input string is a
date or not:

select isdate('05.15.2003');
Result: 1
select isdate('foobar');
Result: 0

Is there a function in plpgsql like that?
Maybe someone has a self-written function that implements that?

I wrote something like you describe for someone else. It installs like a
"contrib" library, i.e.:

put the tarball in your source tree contrib folder
tar -xzf str_validate.tar.gz
cd str_validate
make
make install
psql mydatabase < str_validate.sql

You can grab a copy here:
http://www.joeconway.com/

See the README for (a little) more detail, but for your specific
question above, use is like this:

test=# select str_valid('05.15.2003','timestamp'::regtype);
str_valid
-----------
t
(1 row)

test=# select str_valid('foobar','timestamp'::regtype);
str_valid
-----------
f
(1 row)

Note, the above is for PostgreSQL 7.3.x or 7.4devel. If you are using
7.2.x, grab the version "str_validate for 7.2.X" and use like this:

test=# select str_valid('05.15.2003',(select oid from pg_type where
typname = 'timestamp'));
str_valid
-----------
t
(1 row)

test=# select str_valid('foobar',(select oid from pg_type where typname
= 'timestamp'));
str_valid
-----------
f
(1 row)

HTH,

Joe