SQL 错误 [156] [S0001]：关键字“联合”附近的语法不正确

Question

WITH a AS
(
    SELECT 
        ii.RPTCategory AS Cat,
        YEAR(ii.CreateDate) AS CatYear, MONTH(ii.CreateDate) AS CatMonth,
        COUNT(*) AS CatNo
    FROM 
        InsInvoice ii 
    WHERE
        ii.RPTCategory IN ('12')
    GROUP BY
        ii.RPTCategory, YEAR(ii.CreateDate), MONTH(ii.CreateDate)
),
b AS
(
    SELECT 
        ii.Category AS Cat,
        YEAR(ii.CreateDate) AS CatYear, MONTH(ii.CreateDate) AS CatMonth,
        COUNT(*) AS CatNo
    FROM 
        InsInvoice ii 
    WHERE
        ii.Category IN ('41')
    GROUP BY
        ii.Category, YEAR(ii.CreateDate), MONTH(ii.CreateDate)
)
SELECT *
FROM 
    (a UNION b)

我得到错误

关键字 union 附近的语法不正确

我所做的所有搜索，用户在他们的子 select 语句中使用order by时都会遇到错误，但我没有这样做。 我尝试将其拆分为子 select 语句，而不是使用 with 子句，但我得到了同样的错误。

Answer 1

union的正确用法是：

select a.*
from a
union
select b.*
from b;