本文介紹了字符串中元素的反向順序的處理方法,對大家解決問題具有一定的參考價值,需要的朋友們下面隨著小編來一起學習吧!
問題描述
我有以下字符串:
1119/2/483/11021
我想顛倒該字符串中元素的順序。所需輸出:
11021/483/2/1119
T-SQL 2014版
推薦答案
您需要一個有序的拆分函數,例如(inspiration):
CREATE FUNCTION dbo.SplitOrdered
(
@list nvarchar(max),
@delim nvarchar(10)
)
RETURNS TABLE
WITH SCHEMABINDING
AS
RETURN
(
WITH w(n) AS (SELECT 0 FROM (VALUES (0),(0),(0),(0)) w(n)),
k(n) AS (SELECT 0 FROM w a, w b),
r(n) AS (SELECT 0 FROM k a, k b, k c, k d, k e, k f, k g, k h),
p(n) AS (SELECT TOP (COALESCE(LEN(@list), 0))
ROW_NUMBER() OVER (ORDER BY @@SPID) -1 FROM r),
spots(p) AS
(
SELECT n FROM p
WHERE (SUBSTRING(@list, n, LEN(@delim + 'x') - 1) LIKE @delim OR n = 0)
),
parts(p,val) AS
(
SELECT p, SUBSTRING(@list, p + LEN(@delim + 'x') - 1,
LEAD(p, 1, 2147483647) OVER (ORDER BY p) - p - LEN(@delim))
FROM spots AS s
)
SELECT listpos = ROW_NUMBER() OVER (ORDER BY p),
Item = LTRIM(RTRIM(val))
FROM parts
);
然后您可以在較低版本上使用STRING_AGG()
(如果SQL Server 2017或更高版本)或FOR XML PATH
重新組裝:
SQL Server 2017+
DECLARE @OriginalString nvarchar(255) = N'1119/2/483/11021';
SELECT NewString = STRING_AGG(o.Item, N'/')
WITHIN GROUP (ORDER BY listpos DESC)
FROM dbo.SplitOrdered(@OriginalString, N'/') AS o;
SQL Server<;2017
DECLARE @OriginalString nvarchar(255) = N'1119/2/483/11021';
SELECT NewString = STUFF(
(SELECT N'/' + o.Item
FROM dbo.SplitOrdered(@OriginalString, N'/') AS o
ORDER BY o.listpos DESC
FOR XML PATH(''), TYPE).value(N'./text()[1]', N'nvarchar(max)'),1,1,N'');
示例db<>fiddle
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