根据条件调用 CTE - Case 语句 SQL

Question

我有两个 CTE，它们具有完全相同的数据结构，但从两个不同的表读取数据。基于日期过滤器，我可以在 SQL 中调用 CTE（使用 IF 或 case 语句）。像这样的吗？

with combined_query as
(
 select * from CTE1 
 union all
 select * from CTE2
)
select 
case when date >= '2023-01-01' select * from CTE1
else select * from CTE2 end as criteria
from combined_query

“日期”列在两个 CTE 中均可用

提前致谢。

Answer 1

也许尝试像这样使用

WHERE

？

with combined_query AS (
    SELECT *, 'CTE1' AS source FROM CTE1
    UNION ALL
    SELECT *, 'CTE2' AS source FROM CTE2
)
SELECT *
FROM combined_query
WHERE (date >= '2023-01-01' AND source = 'CTE1')
   OR (date < '2023-01-01' AND source = 'CTE2');