我有一个包含以下类型的表:
Id Parent_id Code Name market
1 NULL 1ex name 1 3
2 1 2ex name 2 3
3 1 3ex name 3 3
4 Null 4ex name 4 1
5 null 5ex name 5 3
6 4 6ex name 6 3
我想从上表中选择code
和name
,以便按以下方式排序:
即。应首先显示id 1(Parent_id),然后显示id 2和3(Child id)。 'parent_id'中的值来自列'id'。
到目前为止,我已经构建了以下查询,我觉得订购父代码和相关的子代码有点困难。
select code,name from tbl_codes A
order by CASE WHEN(A.[Market] = 3) THEN 0 ELSE 1 END
有人可以帮帮我吗。
答案 0 :(得分:2)
试试这个
SELECT code ,
name
FROM tbl_codes A
ORDER BY CASE WHEN ( A.[Market] = 3 ) THEN 0
ELSE 1
END ,
CASE WHEN ( ISNULL(parent_id,0) = 1 ) THEN 0
ELSE 1
END
答案 1 :(得分:1)
递归CTE是构建父/子层次结构的最佳方法,如下所示:
-- Set up test data
CREATE TABLE tbl_codes (id INT , Parent_id INT, Code VARCHAR(3), NAME VARCHAR(12), Market INT)
INSERT tbl_codes
SELECT 1, NULL, '1ex', 'name 1', 3 UNION ALL
SELECT 2, 1 , '2ex', 'name 2', 3 UNION ALL
SELECT 3, 1 , '3ex', 'name 3', 3 UNION ALL
SELECT 4, NULL , '4ex', 'name 4', 1 UNION ALL
SELECT 5, NULL , '5ex', 'name 5', 3 UNION ALL
SELECT 6, 4 , '6ex', 'name 6', 3
CREATE VIEW [dbo].[View_ParentChild]
AS
-- Use a recursive CTE to build a parent/child heirarchy
WITH
RecursiveCTE AS
(
SELECT
id,
name,
parent_id,
Code,
market,
sort = id
FROM
tbl_codes
WHERE
parent_id IS NULL
UNION ALL
SELECT
tbl_codes.id,
tbl_codes.name,
tbl_codes.parent_id,
tbl_codes.Code,
tbl_codes.market,
sort = tbl_codes.parent_id
FROM
tbl_codes
INNER JOIN RecursiveCTE
ON tbl_codes.parent_id = RecursiveCTE.id
WHERE
tbl_codes.parent_id IS NOT NULL
)
SELECT
Code,
NAME,
Market,
Sort
FROM
RecursiveCTE
GO
根据您的要求,我将查询重构为VIEW。
使用视图:
SELECT
*
FROM
dbo.View_ParentChild AS vpc
ORDER BY
CASE WHEN ( Market = 3 ) THEN 0
ELSE 1
END,
sort
它给出了以下结果:
Code NAME Market Sort
---- ------ ------ ----
1ex name 1 3 1
2ex name 2 3 1
3ex name 3 3 1
6ex name 6 3 4
5ex name 5 3 5
4ex name 4 1 4
要了解有关递归CTE的更多信息,请点击here
并且,根据要求,该视图的新版本不使用递归CTE
CREATE VIEW [dbo].[View_ParentChild_v2]
AS
SELECT
id,
Code,
market,
sort
FROM
(
SELECT
id,
name,
parent_id,
Code,
market,
sort = id
FROM
tbl_codes
WHERE
parent_id IS NULL
UNION ALL
SELECT
tbl_codes.id,
tbl_codes.name,
tbl_codes.parent_id,
tbl_codes.Code,
tbl_codes.market,
sort = tbl_codes.parent_id
FROM
tbl_codes
WHERE
tbl_codes.parent_id IS NOT NULL
) AS T
GO
使用如下:
SELECT
*
FROM
View_ParentChild_v2
ORDER BY
CASE WHEN ( Market = 3 ) THEN 0
ELSE 1
END,
sort
nb:使用递归CTE的第一个版本可以处理几乎无限级别的父/子,而版本2只处理一个级别。
答案 2 :(得分:0)
您可以在条目中添加条件。尝试:
SELECT code ,
name ,
CASE WHEN ( A.[Market] = 3 ) THEN 0
ELSE 1
END AS marketOrder ,
CASE WHEN ( parent_id = 1 ) THEN 0
ELSE 1
END AS parentOrder
FROM tbl_codes A
ORDER BY parentOrder ,
marketOrder