通过 union all 使用多个 with 语句答案

【问题标题】：To use multiple with statement by union all通过 union all 使用多个 with 语句
【发布时间】：2014-08-14 20:40:31
【问题描述】：

WITH L1 AS
(
   SELECT
)
SELECT A FROM L1

UNION ALL

SELECT A FROM TABLE

UNION ALL

WITH L2 AS
(
   SELECT
)
SELECT A FROM L2

UNION ALL

WITH L3 AS
(
   SELECT
)
SELECT A FROM L3

我收到一个错误

关键字“with”附近的语法不正确。如果此语句是公用表表达式或 xmlnamespaces 子句，则前面的语句必须以分号结束。"

请帮忙

【问题讨论】：

您不需要 WITH AS 子句。

标签： sql sql-server

【解决方案1】：

您不能在查询表达式的中间中使用WITH。 WITH 用于构建中间查询，供其他查询使用（意味着它不能被多个独立查询使用）。

所以你可能想要这样的东西：

WITH L1 
AS
(
    SELECT ...
),
L2 AS
(
    SELECT ...
),
L3 AS
(
    SELECT ...
)

// begin final query    
SELECT A FROM L1
UNION ALL
SELECT A FROM TABLE
UNION ALL
SELECT A FROM L2
UNION ALL
SELECT A FROM L3

【讨论】：

【解决方案2】：

语法是

With l1 ( a ) as ( Select ... )
   , l2 ( a ) as ( ... )
  Select ... From ...
  Union
  Select ... From ...

【讨论】：

【解决方案3】：

两种方法：

SELECT A FROM L1
UNION ALL
SELECT A FROM L2
UNION ALL
SELECT A FROM L3

或

WITH CTE_L AS
(
    SELECT A FROM L1
    UNION ALL
    SELECT A FROM L2
    UNION ALL
    SELECT A FROM L3
)
SELECT * FROM CTE_L

【讨论】：