Question

我尝试过使用patindex和charindex，但似乎他们都不会轻易做到我想要的。 Charindex只想一次搜索一个符号，而patindex不允许“搜索”索引，不允许我循环查找符号的所有索引。我有什么选择？

Answer 1

没有关于你的“特殊符号”的具体细节，如何存储以及你期望的输出有一些猜测工作，但我认为我的答案的基本原则可以应用。获得所有出现的关键是使用递归CTE和OUTER APPLY。每次CTE循环时，它都会用空格替换一个特殊字符，直到没有特殊字符为止，存储字符的位置。

示例数据：

DECLARE @SpecialSymbols TABLE (Symbol CHAR(1) NOT NULL PRIMARY KEY)
INSERT @SpecialSymbols VALUES ('@'), ('.'), ('['), (']')

DECLARE @TestData TABLE (StringToTest VARCHAR(100))
INSERT @TestData VALUES 
    ('test 1 [Using Square Brackets]'), 
    ('[Test2@EmailAddress.com]'), 
    ('No Special Symbols')

实际查询

;WITH CTE AS
(   SELECT  *, STUFF(StringToTest, Position, 1, ' ') [ReworkedString]
    FROM    @TestData
            OUTER APPLY
            (   SELECT  CHARINDEX(Symbol, StringToTest) [Position], Symbol
                FROM    @SpecialSymbols
            ) Symbols
    WHERE   Position > 0
    UNION ALL
    SELECT  StringToTest, Symbols.Position, Symbols.Symbol, STUFF(ReworkedString, Symbols.Position, 1, ' ') [ReworkedString]
    FROM    CTE
            OUTER APPLY
            (   SELECT  CHARINDEX(Symbol, ReworkedString) [Position], Symbol
                FROM    @SpecialSymbols
                WHERE   Symbol = CTE.Symbol
            ) Symbols
    WHERE   Symbols.Position > 0
)

-- CTE NOW LOOKS LIKE:
--  | test 1 [[Using Square Brackets]   |   8   |   [   | test 1  [Using Square Brackets]
--  | test 1 [[Using Square Brackets]   |   30  |   ]   | test 1 [[Using Square Brackets 
--  | [Test2@EmailAddress.com]          |   20  |   .   | [Test2@EmailAddress com]
--  | [Test2@EmailAddress.com]          |   7   |   @   | [Test2 EmailAddress.com]
--  | [Test2@EmailAddress.com]          |   1   |   [   |  Test2@EmailAddress.com]
--  | [Test2@EmailAddress.com]          |   24  |   ]   | [Test2@EmailAddress.com 
--  | test 1 [[Using Square Brackets]   |   9   |   [   | test 1   Using Square Brackets]

SELECT  a.StringToTest, COALESCE(Location, '') [SpecialSymbolLocations]
FROM    @TestData a
        LEFT JOIN
        (   SELECT  DISTINCT
                    StringToTest,
                    -- THIS MERELY CONCATENATES ROWS INTO COLUMNS TO GET COMMA SEPARATED LIST
                    STUFF(( SELECT  ', ' + CONVERT(VARCHAR, Position)
                            FROM    CTE b
                            WHERE   a.StringToTest = b.StringToTest
                            ORDER BY Position
                            FOR XML PATH('')
                    ), 1, 2, '') [Location] 
            FROM    CTE a
        ) b
            ON a.StringToTest = b.StringToTest

CTE可以随意操作，但为了完整起见，我使用SQL server XML Extension to concatenate特殊符号的位置添加了一个最终查询到逗号分隔列表中并将它们放在每个旁边原始字符串。所以最终的输出结果如下：

| StringToTest                      | SpecialSymbolLocations    |
|-----------------------------------|---------------------------|
| test 1 [[Using Square Brackets]   | 8, 9, 31                  |
| [Test2@EmailAddress.com]          | 1, 7, 20, 24              |
| No Special Symbols                |                           |

如何在varchar中找到所有特殊符号的位置？

1 个答案: