SQL问题,OUTER JOIN,检索数据问题答:select coalesce(t1.ym, t2.ym, t3.ym) ym, coalesce(t1.key1, t2.key1, t3.key) key1,t0.amt, t1.amt1, t2.amt2, t3.amt3 from table31 t1 full join table32 t2 on t1.key1=t2.key1 and t1.ym=t2.ym full join table33 t3 on coalesce(t1.key1,t2.key1)=t3....