请问个SQL语句写法

请教个SQL语句写法
表A中有字段a_ID,b_ID
表B中有字段ID,DESC
选出2个DESC，条件为a_ID   =   B.ID,   b_ID   =   B.ID
我不清楚该如何实现，用UNION么？谢谢指点



------解决方案--------------------
或者


Select T1.[DESC] As a_DESC, T2.[DESC] As b_DESC
From A , B T1, B T2
Where A.a_ID = T1.ID And A.b_ID = T2.ID