Oracle排序取第一条数据

需要更新套组的大单位， 规则是取第一个学员（套组ID最小）的单位信息。

采用按照SUITEID排序取第一条方法。

UPDATE sim_big_suite u SET u.org_code = (
SELECT SUBSTR(x.pilot_unit,1,4) FROM(
SELECT n.* FROM sim_student_assign n WHERE
 n.big_suite_no = 192 AND
--u.big_suite_no = n.big_suite_no AND  
n.ac_type_code = 14 
AND n.fixed_year = '2013上半年' AND n.train_com = 1001 AND n.position = 'L'
ORDER BY n.suite_id
)x WHERE ROWNUM = 1
)WHERE u.ac_type_code = 14 AND u.fixed_year = '2013上半年' AND u.train_com = 1001;