SQL - Delete in Two Tables

delete from a.doc_data where sur_doc_nbr in (select sur_doc_nbr from a.doc where deld=1)
delete from a.doc_attr where sur_doc_nbr in (select sur_doc_nbr from a.doc where deld=1)
delete from a.doc where deld=1

aggregates not allowed in WHERE clause

use HAVING, e.g.

SELECT player_name, AVG(score) as score FROM NBA.score_box WHERE box_year > 2004 GROUP BY player_name HAVING count(Game) > 100 ORDER BY score