select t1,t2,a t3 from tablename
union all
select t1,t2,b t3 from tablename
union all
select t1,t2,c t3 from tablename
union all
select t1,t2,b t3 from tablename
union all
select t1,t2,c t3 from tablename
调试欢乐多
select t1,t2,'a' t3,a t4 from tablename
union all
select t1,t2,'b' t3,b t4 from tablename
union all
select t1,t2,'c' t3,c t4 from tablename
Into 表名 values (公用字段,字段1)
......
Into 表名 values (公用字段,字段n)
select 公用字段,字段1,...字段n
from 表名;