我有三个问题如下：
select sum(prod) as Production ,sum(rej) as Rejection
where machinename='A' from data
select sum(prod) as Production ,sum(rej) as Rejection
where machinename='B' from data
select sum(prod) as Production ,sum(rej) as Rejection
where machinename='C' from data
我希望加入这些查询以获得单行输出。