请问Mysql不同字段有不同的记录返回，要放在一起的话如何查询？

Question

A表字段单独查询有3条记录返回
B表字段单独查询有8条记录返回
目前这两个表都是无主键和外键
如果要组合起来的话，表的结构应该如何设计，模型如何搭建

Answer 1

select a as a1,b as a2 ,c as a3 from t1 where xx=xx
union 
select b1 as a1,b2 as a2 ,b3 as a3 from t1 where xx=xx