SQL中如何把union all查询出来的语句用count语句来统计数量

已经用union all的语句查询出来数据，数据有点大，想用count语句来统计相同序号的数量，具体该怎么包进去

union all 的语句
select a.table1 from a
union all
select b.table2 from b
怎么把union all包进count里

select count(1),a.table1 from a
union all
select b.table2 from b

把union all包进count里的语句：

select count(*) from (
select a.table1 from a
union all
select b.table2 from b ) c

如果只是简单获取union all总数：

select
count(*)
from(
select a.table1 from a
union all
select b.table2 from b
)t

如果需要去重获取相同内容分别的数量：

select
myName,
count(*)myNum
from(
select a.table1 as myName from a
union all
select b.table2 as myName from b
)t 
group by myName 

SELECT tb, COUNT(1) AS num FROM(
SELECT a.table1 AS tb FROM a
UNION ALL
SELECT b.table2 AS tb FROM b
)tmp GROUP BY tb