Loop over an PostgreSQL array within a SELECT query, instead of within a PLPGSQL function

I have a text[] ARRAY column within a PostgreSQL table and I need to run char_length() on each element inside the array within a SELECT query (normal SQL, not plpgsql) so that if any of the elements is more than 25 characters long, 开发者_如何学JAVAthe SELECT returns 't' and 'f' otherwise. I know I can loop over the text[] within a custom plpgsql function but due to other reasons I need to find a way to do this in SQL directly.

Is it possible?

As of PostgreSQL 8.4, you can use the UNNEST function:

SELECT MAX((char_length(string) > 25)::INT)::BOOLEAN
FROM (
    SELECT my_array,UNNEST(my_array) AS string
    FROM my_table
) AS x
GROUP BY my_array;

You could use unnest to break open the array and then some simple length and exists stuff:

select exists(
    select 1
    from (
        select unnest(ar) as x
        from table_name
    ) as t
    where length(x) > 25
)

The exists and select 1 business is just a convenient way to collapse result set to a single boolean (I'm sure there are other ways).