在基于SET的SQL中从VARCHAR字段中提取段/值的最佳方法

时间：2013-01-29 13:02:37

标签： sql sql-server regex tsql sql-server-2008-r2

采用以下示例数据：

SELECT 'HelpDesk Call Reference F0012345, Call Update, 40111' AS [Subject]
UNION ALL
SELECT 'HelpDesk Call Reference F0012346, Call Resolved, 40112' AS [Subject]
UNION ALL
SELECT 'HelpDesk Call Reference F0012347, New call logged, 40113' AS [Subject]

我想要做的是如下提取这些数据：

This is how i need to select the data

如您所见，我需要提取Ref，Type＆amp; OurRef作为单独的列，以确保在处理生成的电子邮件时有效的基于SQL的SQL。

通常对于这种情况，我会使用如下函数：

CREATE FUNCTION dbo.fnParseString (
    @Section SMALLINT ,
    @Delimiter CHAR ,
    @Text VARCHAR(MAX)
)
RETURNS VARCHAR(8000)
AS 
    BEGIN
        DECLARE @NextPos SMALLINT;
        DECLARE @LastPos SMALLINT;
        DECLARE @Found SMALLINT;

        SELECT  @NextPos = CHARINDEX(@Delimiter, @Text, 1) ,
                @LastPos = 0 ,
                @Found = 1

        WHILE @NextPos > 0
            AND ABS(@Section) <> @Found 
            SELECT  @LastPos = @NextPos ,
                    @NextPos = CHARINDEX(@Delimiter, @Text, @NextPos + 1) ,
                    @Found = @Found + 1

        RETURN LTRIM(RTRIM(CASE
            WHEN @Found <> ABS(@Section) OR @Section = 0 THEN NULL
            WHEN @Section > 0 THEN SUBSTRING(@Text, @LastPos + 1, CASE WHEN @NextPos = 0 THEN DATALENGTH(@Text) - @LastPos ELSE @NextPos - @LastPos - 1 END)
            ELSE SUBSTRING(@Text, @LastPos + 1, CASE WHEN @NextPos = 0 THEN DATALENGTH(@Text) - @LastPos ELSE @NextPos - @LastPos - 1 END)
        END))
    END

例如i然后在ref之前替换空格以包含逗号并按如下方式拆分：

WITH    ExampleData
          AS ( SELECT   'HelpDesk Call Reference F0012345, Call Update, 40111' AS [Subject]
               UNION ALL
               SELECT   'HelpDesk Call Reference F0012346, Call Resolved, 40112'
               UNION ALL
               SELECT   'HelpDesk Call Reference F0012347, New call logged, 40113'
             )
    SELECT  dbo.fnParseString(2, ',', REPLACE([Subject], 'HelpDesk Call Reference ', 'HelpDesk Call Reference, ')) AS [Ref] ,
            dbo.fnParseString(3, ',', REPLACE([Subject], 'HelpDesk Call Reference ', 'HelpDesk Call Reference, ')) AS [Type] ,
            dbo.fnParseString(4, ',', REPLACE([Subject], 'HelpDesk Call Reference ', 'HelpDesk Call Reference, ')) AS [OurRef]
    FROM    ExampleData

正如你所看到的，我有一个解决方案可以获得我最终的结果，但使用凌乱的udf并不理想＆amp;我想知道是否有更好的方式做这样的事情 - 也许是内联正则表达式？即我认为PATINDEX()接受正则表达式作为搜索字符串 - 这与SUBSTRING()一起可以做我需要的但我真的不知道从哪里开始？

编辑：请注意，这是一个简化的示例，主题是可变的，我也将采用相同的技术来解析身体，身体将有8项数据，我需要使用各种分隔符进行解析，因此这排除了ParseName()的使用，因为它只允许4个部分，并且我不能使用固定长度（即substring()），因为长度将是非常多变（特别是如果涉及不同的帮助台（他们是） - 这就是为什么我在思考PATINDEX()＆amp; SUBSTRING()

的原因

3 个答案:

答案 0 :(得分：3)

我建议使用它：

;WITH CTE
AS
(
SELECT 'HelpDesk Call Reference F0012345, Call Update, 40111' AS [Subject]
UNION ALL
SELECT 'HelpDesk Call Reference F0012346, Call Resolved, 40112' AS [Subject]
UNION ALL
SELECT 'HelpDesk Call Reference F0012347, New call logged, 40113' AS [Subject]
)
, CTEPart
as
(
SELECT [Subject], REPLACE(SUBSTRING([Subject], 25, 1000), ', ', '.') Part
FROM CTE
)
SELECT
    [Subject],
    PARSENAME(Part, 1) AS [Ref],
    PARSENAME(Part, 2) AS [Type],
    PARSENAME(Part, 3) AS [OurRef]
FROM CTEPart

答案 1 :(得分：1)

经过额外的工作，我们决定不在Art的答案中使用这种方法（即使它有效）。

我们需要一种更强大的验证和提取子串的方法，所以我通过CLR路由去了正则表达式（感谢Pondlife指示我指向正确的方向）。

我采取的方法如下：

首先我编译了以下CLR :(从C＃示例Here转换为VB） 

Imports System.Data
Imports System.Data.SqlClient
Imports System.Data.SqlTypes
Imports Microsoft.SqlServer.Server
Imports System.Text.RegularExpressions
Imports System.Text

Partial Public Class UserDefinedFunctions

    Public Shared ReadOnly Options As RegexOptions = RegexOptions.IgnorePatternWhitespace Or RegexOptions.Multiline

    <SqlFunction()> _
    Public Shared Function RegexMatch(ByVal input As SqlChars, ByVal pattern As SqlString) As SqlBoolean
        Dim regex As New Regex(pattern.Value, Options)
        Return regex.IsMatch(New String(input.Value))
    End Function

    <SqlFunction()> _
    Public Shared Function RegexReplace(ByVal expression As SqlString, ByVal pattern As SqlString, ByVal replace As SqlString) As SqlString
        If expression.IsNull OrElse pattern.IsNull OrElse replace.IsNull Then
            Return SqlString.Null
        End If

        Dim r As New Regex(pattern.ToString())
        Return New SqlString(r.Replace(expression.ToString(), replace.ToString()))
    End Function

    ' returns the matching string. Results are separated by 3rd parameter
    <SqlFunction()> _
    Public Shared Function RegexSelectAll(ByVal input As SqlChars, ByVal pattern As SqlString, ByVal matchDelimiter As SqlString) As SqlString
        Dim regex As New Regex(pattern.Value, Options)
        Dim results As Match = regex.Match(New String(input.Value))

        Dim sb As New StringBuilder()
        While results.Success
            sb.Append(results.Value)

            results = results.NextMatch()

            ' separate the results with newline|newline
            If results.Success Then
                sb.Append(matchDelimiter.Value)
            End If
        End While

        Return New SqlString(sb.ToString())

    End Function

    ' returns the matching string
    ' matchIndex is the zero-based index of the results. 0 for the 1st match, 1, for 2nd match, etc
    <SqlFunction()> _
    Public Shared Function RegexSelectOne(ByVal input As SqlChars, ByVal pattern As SqlString, ByVal matchIndex As SqlInt32) As SqlString
        Dim regex As New Regex(pattern.Value, Options)
        Dim results As Match = regex.Match(New String(input.Value))

        Dim resultStr As String = ""
        Dim index As Integer = 0

        While results.Success
            If index = matchIndex Then
                resultStr = results.Value.ToString()
            End If

            results = results.NextMatch()

            index += 1
        End While

        Return New SqlString(resultStr)

    End Function

End Class

我按如下方式安装了此CLR： 

EXEC sp_configure 
    'clr enabled' ,
    '1'

GO

RECONFIGURE
USE [db_Utility]

GO
CREATE ASSEMBLY SQL_CLR_RegExp FROM 'D:\Program Files\Microsoft SQL Server\MSSQL10_50.MSSQLSERVER\MSSQL\Binn\SQL_CLR_RegExp.dll' WITH
PERMISSION_SET = SAFE

GO
-- =============================================
-- Returns 1 or 0 if input matches pattern
-- VB function: RegexMatch(ByVal input As SqlChars, ByVal pattern As SqlString) As SqlBoolean
-- =============================================
CREATE FUNCTION [dbo].[RegexMatch]
    (
      @input [nvarchar](MAX) ,
      @pattern [nvarchar](MAX)
    )
RETURNS [bit]
    WITH EXECUTE AS CALLER
AS EXTERNAL NAME 
    [SQL_CLR_RegExp].[SQL_CLR_RegExp.UserDefinedFunctions].[RegexMatch]
GO

-- =============================================
-- Returns a comma separated string of found objects
-- VB function: RegexReplace(ByVal expression As SqlString, ByVal pattern As SqlString, ByVal replace As SqlString) As SqlString
-- =============================================
CREATE FUNCTION [dbo].[RegexReplace]
    (
      @expression [nvarchar](MAX) ,
      @pattern [nvarchar](MAX) ,
      @replace [nvarchar](MAX)
    )
RETURNS [nvarchar](MAX)
    WITH EXECUTE AS CALLER
AS EXTERNAL NAME 
    [SQL_CLR_RegExp].[SQL_CLR_RegExp.UserDefinedFunctions].[RegexReplace]
GO
-- =============================================
-- Returns a comma separated string of found objects
-- VB function: RegexSelectAll(ByVal input As SqlChars, ByVal pattern As SqlString, ByVal matchDelimiter As SqlString) As SqlString
-- =============================================
CREATE FUNCTION [dbo].[RegexSelectAll]
    (
      @input [nvarchar](MAX) ,
      @pattern [nvarchar](MAX) ,
      @matchDelimiter [nvarchar](MAX)
    )
RETURNS [nvarchar](MAX)
    WITH EXECUTE AS CALLER
AS EXTERNAL NAME 
    [SQL_CLR_RegExp].[SQL_CLR_RegExp.UserDefinedFunctions].[RegexSelectAll]
GO
-- =============================================
-- Returns finding matchIndex of a zero based index
-- RegexSelectOne(ByVal input As SqlChars, ByVal pattern As SqlString, ByVal matchIndex As SqlInt32) As SqlString
-- =============================================
CREATE FUNCTION [dbo].[RegexSelectOne]
    (
      @input [nvarchar](MAX) ,
      @pattern [nvarchar](MAX) ,
      @matchIndex [int]
    )
RETURNS [nvarchar](MAX)
    WITH EXECUTE AS CALLER
AS EXTERNAL NAME 
    [SQL_CLR_RegExp].[SQL_CLR_RegExp.UserDefinedFunctions].[RegexSelectOne]
GO

然后我编写了以下包装函数以简化使用： 

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author:      <Jordon Pilling>
-- Create date: <30/01/2013>
-- Description: <Calls RegexSelectOne with start and end text and cleans the result>
-- =============================================
CREATE FUNCTION [dbo].[RegexSelectOneWithScrub]
(
    @Haystack VARCHAR(MAX),
    @StartNeedle VARCHAR(MAX),
    @EndNeedle VARCHAR(MAX)
)
RETURNS VARCHAR(MAX)
AS
BEGIN
    DECLARE @ReturnStr VARCHAR(MAX)

    --#### Extract text from HayStack using Start and End Needles
    SET @ReturnStr = dbo.RegexSelectOne(@Haystack, REPLACE(@StartNeedle, ' ','\s') + '((.|\n)+?)' + REPLACE(@EndNeedle, ' ','\s'), 0)

    --#### Remove the Needles
    SET @ReturnStr = REPLACE(@ReturnStr, @StartNeedle, '')
    SET @ReturnStr = REPLACE(@ReturnStr, @EndNeedle, '')

    --#### Trim White Space
    SET @ReturnStr = LTRIM(RTRIM(@ReturnStr))

    --#### Trim Line Breaks and Carriage Returns
    SET @ReturnStr = dbo.SuperTrim(@ReturnStr)

    RETURN @ReturnStr

END
GO

允许使用如下： 

DECLARE @Subject VARCHAR(250) = 'HelpDesk Call Reference F0012345, Call Update, 40111' 
DECLARE @Ref VARCHAR(250) = NULL

IF dbo.RegexMatch(@Subject, '^HelpDesk\sCall\sReference\sF[0-9]{7},\s(Call\sResolved|Call\sUpdate|New\scall\slogged),(|\s+)([0-9]+|unknown)$') = 1
    SET @Ref = ISNULL(dbo.RegexSelectOneWithScrub(@Subject, 'HelpDesk Call Reference', ','), 'Invalid (#1)')
ELSE
    SET @Ref = 'Invalid (#2)'

SELECT @Ref

这可以更快地用于多次搜索，并且在处理大量具有不同开始和结束短语等的文本时更加强大。

答案 2 :(得分：0)

此示例是Oracle查询。使用的所有函数都是ANSI SQL标准，可以在任何SQL中使用。此示例仅剪切字符串的REF部分。你只需要重复Type，OutRef等的所有步骤......这个例子假设你的ref总是包含0-zero，并且在ref之后总会有'，'，可以用空格或任何其他字符替换。使用NVL（）cna：INSTR（str，NVL（'，'，''）...）。我认为这种方法更通用，然后将值硬编码到SUBSTR ......：

SELECT str, SUBSTR(str, ref_start_pos, ref_end_pos) final_ref
 FROM
 (
  SELECT str, ref_start_pos, INSTR(str, ',', ref_start_pos)-ref_start_pos AS ref_end_pos
    FROM
    (
     SELECT str, INSTR(str, '0')-1 AS ref_start_pos
       FROM
       (
        SELECT 'HelpDesk Call Reference F0012345, Call Update, 40111' AS str
          FROM dual
        UNION ALL
        SELECT 'HelpDesk Call Reference F0012346, Call Resolved, 40112' 
          FROM dual
       )
     )
   )
  /

  SQL>

  STR                                                    |  FINAL_REF
  ------------------------------------------------------------------------
  HelpDesk Call Reference F0012345, Call Update, 40111   |  F0012345
  HelpDesk Call Reference F0012346, Call Resolved, 40112 |  F0012346

SQL Server版本（由OP添加）：

SELECT  [str] ,
        SUBSTRING([str], ref_start_pos, ref_end_pos) AS final_ref
FROM    ( SELECT    [str] ,
                    ref_start_pos ,
                    CHARINDEX(',', [str], ref_start_pos) - ref_start_pos AS ref_end_pos
          FROM      ( SELECT    [str] ,
                                CHARINDEX('Reference', [str]) + 10 AS ref_start_pos
                      FROM      ( SELECT    'HelpDesk Call Reference F0012345, Call Update, 40111' AS [str]
                                  UNION ALL
                                  SELECT    'HelpDesk Call Reference F0012346, Call Resolved, 40112' AS [str]
                                ) AS T1
                    ) AS T2
        ) AS T3
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