SQL participa em uma subconsulta
SELECT *
FROM
( SELECT ... FROM ... ) q1
INNER JOIN
( SELECT ... FROM ... ) q2
ON q1.colname = q2.colname
Embarrassed Elk
SELECT *
FROM
( SELECT ... FROM ... ) q1
INNER JOIN
( SELECT ... FROM ... ) q2
ON q1.colname = q2.colname
(select coalesce((select name from object_value where object_id = addtl_type.id
and object_type_id = @object_type_des_UDF
and language_id = @language_id),addtl_type.name) from addtl_type
where id = (select n_value from pr_addtl_data where pr_id = PR.ID and
data_field_id = (select id from data_fields where name = 'Category'))) as 'Category',