Access两个表怎样按条件合并查询

现有一mdb数据库，内有两个表A和B，表A中有字段a1,a2,a3,a4和其他字段，表B中有字段b1,b5和其他字段，两个表第1字段a1,b1都为考号，现按考号查询并合并，下列代码有误，怎么改？万分感谢！

kkkk=request("kkkk")
if kkkk<> empty then
sql="select A.a1,A.a2,A.a3,A.a4,B.b5 from A,B where A.a1='"& kkkk &"' and B.b1='"& kkkk &"'"
set rs=GetMdbStaticRecordset("db.mdb",sql)

sql="select A.a1,A.a2,A.a3,A.a4,B.b5 from A,B where A.a1=B.b1 and A.a1='" & kkkk & "'"

select * from (select * from 表1 union select * from 表2) as [%$##@_alias];