If you want to describe table like DESCRIBE in MySQL you can use this:
$sql = <<<SQL
SELECT column_name,data_type,column_default,is_nullable
FROM
information_schema.tables AS t
JOIN
information_schema.columns AS c ON
t.table_catalog=c.table_catalog AND
t.table_schema=c.table_schema AND
t.table_name=c.table_name
WHERE
t.table_name='TABLE-NAME'
SQL;