Question

我想编写如下查询：

select top 1 * from table_A 
Join table B ---some more table is possible
where conditon_1
order by create_date
union all
select top 1 * from table B 
---some more table is possible
where conditon_2
order by create_date

因此，我需要根据不同的条件从两个选择查询中获取最新记录，然后进行全部合并。

Answer 1

您不能直接这样做。将CTE用于第2个查询

with
cte1 as
(
    select top 1 * from table_A 
    Join table B ---some more table is possible
    where conditon_1
    order by create_date
),
cte2 as
(
    select top 1 * from table B 
    ---some more table is possible
    where conditon_2
    order by create_date
)
select * from cte1
union all
select * from cte2

Answer 2

您可以按照以下说明重新编写查询

SELECT * FROM
(select top 1 * from table_A 
Join table B ---some more table is possible
where conditon_1
order by create_date) as t1

UNION ALL

SELECT * FROM 
(select top 1 * from table B 
---some more table is possible
where conditon_2
order by create_date) as t2

查询以从不同的选择查询中获取最新记录，然后合并所有

2 个答案: