SELECT t1.tongji FROM tab1 t1 LEFT JOIN tab1 t2 ON t1.AID=t2.FAID WHERE t2.AID=3

------解决方案--------------------

查询湖北的tongji字段：
SELECT tongji FROM Tab1 WHERE AREA='湖北'

查询aid是3的父栏的tongji字段
SELECT tongji FROM Tab1 WHERE aid IN (SELECT faid FROM Tab1 WHERE aid=3)