How to force Postgres to calculate MAX(boolean)

"Andrus" <noeetasoftspam@online.ee> writes:

MAX(boolean) should return true if its argument evaluates true for at least
one row.

We call it bool_or() ...

regards, tom lane

Andrus wrote:

I try to convert code from other database to Postgres.

CREATE TABLE test(test BOOLEAN);
SELECT MAX(test) FROM test;

causes error

ERROR: function max(boolean) does not exist
HINT: No function matches the given name and argument types. You may need
to add explicit type casts.

I tried
SELECT MAX(test:integer)::boolean FROM test;

but this casuses error

ERROR: cannot cast type boolean to integer

I have lot of MAX() functions applied to boolean expressions.

How to force Postgres to calculate MAX(boolean) ?
MAX(boolean) should return true if its argument evaluates true for at least
one row.

Use bool_or(boolean) instead.
Bye

I try to convert code from other database to Postgres.

CREATE TABLE test(test BOOLEAN);
SELECT MAX(test) FROM test;

causes error

ERROR: function max(boolean) does not exist
HINT: No function matches the given name and argument types. You may need
to add explicit type casts.

I tried
SELECT MAX(test:integer)::boolean FROM test;

but this casuses error

ERROR: cannot cast type boolean to integer

I have lot of MAX() functions applied to boolean expressions.

How to force Postgres to calculate MAX(boolean) ?

MAX(boolean) should return true if its argument evaluates true for at least
one row.

Have you looked into creating a suitable aggregate function yourself?

\h CREATE AGGREGATE

http://www.postgresql.org/docs/current/static/xaggr.html
--
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