Exemple de manipulation de chaînes sensible aux caractères supplémentaires
Cet exemple pour SQL Server illustre un traitement de chaînes sensible aux caractères supplémentaires. Cet exemple illustre l'implémentation de cinq fonctions de chaîne Transact-SQL qui procurent les mêmes fonctions de manipulation de chaînes que les fonctions intégrées, mais avec une capacité additionnelle autorisant la gestion des chaînes de caractères Unicode et supplémentaires. Les cinq fonctions sont lens(), lefts(), rights(), subs() et replace_s(), qui sont équivalentes aux fonctions intégrées LEN(), LEFT(), RIGHT(), SUBSTRING() et aux fonctions de chaîne REPLACE().
Configuration préalable requise
Pour créer et exécuter ce projet, les logiciels suivants doivent être installés :
SQL Server ou SQL Server Express. Vous pouvez vous procurer gratuitement SQL Server Express à partir du site Web SQL Server Express Documentation and Samples (en anglais)
Base de données AdventureWorks qui est disponible sur le site Web du Centre pour les développeurs SQL Server
Le Kit de développement logiciel .NET Framework SDK 2.0 ou version ultérieure, ou Microsoft Visual Studio 2005 ou version ultérieure. Vous pouvez vous procurer gratuitement le Kit de développement logiciel .NET Framework SDK.
De plus, les conditions suivantes doivent être réunies :
L'intégration du CLR doit être activée sur l'instance SQL Server que vous utilisez.
Pour activer l'intégration du CLR, effectuez les étapes suivantes :
Activation de l'intégration du CLR
- Exécutez les commandes Transact-SQL suivantes :
sp_configure 'clr enabled', 1
GO
RECONFIGURE
GO
[!REMARQUE]
Pour activer l'intégration du CLR, vous devez disposer de l'autorisation de niveau serveur ALTER SETTINGS qui est attribuée implicitement aux membres des rôles serveur fixes sysadmin et serveradmin.
La base de données AdventureWorks doit être installée sur l'instance SQL Server que vous utilisez.
Si vous n'êtes pas administrateur de l'instance SQL Server utilisée, vous devez demander à un administrateur de vous accorder l'autorisation CreateAssembly pour terminer l'installation.
Génération de l'exemple
Créez et exécutez l'exemple à l'aide des instructions suivantes :
Ouvrez une invite de commandes Visual Studio ou .NET Framework.
Si nécessaire, créez un répertoire pour votre exemple. Pour cet exemple, nous utiliserons C:\MySample.
Puisque cet exemple requiert un assembly signé, créez une clé asymétrique en tapant la commande :
sn -k SampleKey.snk
Compilez l'exemple de code à partir de l'invite de ligne de commande en exécutant l'un des éléments suivants, selon le langage choisi.
Vbc /reference:C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Data.dll,C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.dll,C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Xml.dll /keyfile:Key.snk /target:library SurrogateStringFunction.vb
Csc /reference:C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Data.dll /reference:C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.dll /reference:C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.XML.dll /keyfile:Key.snk /target:library SurrogateStringFunction.cs
Copiez le code d'installation Transact-SQL dans un fichier et enregistrez-le sous Install.sql dans le répertoire d'exemple.
Déployez l'assembly et la procédure stockée en exécutant
- sqlcmd -E -I -i install.sql -v root = "C:\MySample\"
Copiez le script de la commande de test Transact-SQL dans un fichier et enregistrez-le sous test.sql dans le répertoire d'exemple.
Exécutez le script de test avec la commande suivante
- sqlcmd -E -I -i test.sql
Copiez le script de nettoyage Transact-SQL dans un fichier et enregistrez-le sous cleanup.sql dans le répertoire d'exemple.
Exécutez le script avec la commande suivante
- sqlcmd -E -I -i cleanup.sql
Exemple de code
Voici les listes de code pour cet exemple.
C#
using System;
using System.Globalization;
using System.Text;
/// <summary>
/// Include several string functions for T-SQL to manipulate surrogate characters.
/// </summary>
public sealed class SurrogateStringFunction
{
/// <summary>
///
/// </summary>
private SurrogateStringFunction()
{}
/// <summary>
/// LenS is equal to T-SQL string function LEN() which returns the number
/// of characters, rather than the number of bytes, of the given string expression.
/// </summary>
/// <param name="value">The input string.</param>
/// <returns>The number of characters in the string.</returns>
public static long LenS(String value)
{
if (value == null) throw new ArgumentNullException("value");
int[] myIndex;
// Remove trailing spaces for situations when the Transact-SQL variable or table column
// uses a fixed length datatype such as nchar(50).
// If the trailing spaces are not excluded, this function will return 50 which is not
// correct or expected.
myIndex = StringInfo.ParseCombiningCharacters(value.TrimEnd());
return (null != myIndex) ? myIndex.Length : 0;
}
/// <summary>
/// SubS only support character expression of T-SQL funciton SUBSTRING()
/// which returns part of a string.
/// </summary>
/// <param name="value">The input string.</param>
/// <param name="start">The position of the first character that will be returned.</param>
/// <param name="length">The number of characters to return.</param>
/// <returns>The string found at the starting position for the specified
/// number characters.</returns>
public static String SubS(String value, int start, int length)
{
if (value == null) throw new ArgumentNullException("value");
if (length < 0)
throw new ArgumentException("Invalid length parameter passed to the substring function.");
// In Transact-SQL, the substring method initializes to 1. So, start should be initialized to at least 1.
// Length also has to be at least 1 or the Transact-SQL result would be an empty string.
if ((start + length) <= 1)
return (String.Empty);
// The 2 if statements below guarentee that the result will match the substring function in
// Transact-SQL which will initialize start to 1 by subtracting from the length.
if (start <= 0 && length > 0)
length--;
if ((start <= 0))
{
length = length + start;
start = 1;
}
int[] myIndex;
myIndex = StringInfo.ParseCombiningCharacters(value);
int NumOfIndexes = (null != myIndex) ? myIndex.Length : 0;
start--;
if ((0 <= start) && (start < NumOfIndexes))
{
int lastIndex = start + length;
// if we are past the last char, then we get the string
// up to the last char
if (lastIndex > (NumOfIndexes - 1))
{
return value.Substring(myIndex[start]);
}
else
{
return value.Substring(myIndex[start], myIndex[lastIndex] - myIndex[start]);
}
}
else
{
return String.Empty;
}
}
//
//
/// <summary>
/// LeftS is equal to T-SQL string function LEFT() which returns the left
/// part of a character string with the specified number of characters.
/// </summary>
/// <param name="value">The input string.</param>
/// <param name="start">The position of the first character that will be returned.</param>
/// <param name="length">The number of characters to return.</param>
/// <returns>The string found at the starting position for n-length.</returns>
public static String LeftS(String value, int length )
{
if (length < 0)
throw new ArgumentException("length must be a positive integer");
return SubS(value, 1, length);
}
// RightS is equal to T-SQL string function RIGHT() which returns the right
// part of a character string with the specified number of characters.
public static String RightS(String value, int length)
{
if (length < 0)
throw new NotSupportedException("length must be a positive integer");
if (value == null) throw new ArgumentNullException("value");
int[] myIndex;
myIndex = StringInfo.ParseCombiningCharacters(value);
int numOfIndexes = (null != myIndex) ? myIndex.Length : 0;
if (numOfIndexes <= length)
return value;
if (length == 0) return String.Empty;
int virtualStartIndex = numOfIndexes - length;
int physicalStartIndex = myIndex[virtualStartIndex];
return value.Substring(physicalStartIndex);
}
//
// ReplaceS is equal to T-SQL string function REPLACE() which replaces all
// occurrences of the second given string expression in the first string expression
// with a third expression.
//
public static String ReplaceS(String value, String replaceValue, String newValue)
{
StringBuilder result = new StringBuilder(value.Length);
int[] myIndex;
int i = 0;
String upperValue = value.ToUpper(CultureInfo.CurrentUICulture);
String upperReplaceValue = replaceValue.ToUpper(CultureInfo.CurrentUICulture);
myIndex = StringInfo.ParseCombiningCharacters(upperValue);
while (i < value.Length)
{
int possibleMatch = upperValue.IndexOf(upperReplaceValue, i);
if (possibleMatch < 0)
{
result.Append(value.Substring(i));
break;
}
else
{
//Ensure we're not matching a partial surrogate
int surrogateIndex = Array.IndexOf<int>(myIndex, possibleMatch);
if (surrogateIndex < 0)
{
//We've matched in the middle of a surrogate, skip this match
//as it is not valid.
int nextStart = possibleMatch + 1;
result.Append(value.Substring(i, nextStart-i));
i = nextStart;
}
else
{
//This is a valid match. Make the substitution.
result.Append(value.Substring(i, possibleMatch - i));
result.Append(newValue);
i = possibleMatch + replaceValue.Length;
}
}
}
return result.ToString();
}
}
Visual Basic
Imports Microsoft.VisualBasic
Imports System
Imports System.Collections
Imports System.Data
Imports System.Diagnostics
Imports System.Globalization
Imports System.Text
''' <summary>
''' Include several string functions for T-SQL to manipulate surrogate characters.
''' </summary>
Public NotInheritable Class SurrogateStringFunction
''' <summary>
''' Empty default constructor
''' </summary>
Private Sub New()
End Sub
''' <summary>
''' LenS is equal to T-SQL string function LEN() which returns the number
''' of characters, rather than the number of bytes, of the given string expression.
''' </summary>
''' <param name="value">The input string.</param>
''' <returns>The number of characters in the string.</returns>
<Microsoft.SqlServer.Server.SqlFunction()> _
Public Shared Function LenS(ByVal value As String) As Long
If value Is Nothing Then
Throw New ArgumentNullException("value")
End If
Dim myIndex() As Integer
' Remove trailing spaces for situations when the Transact-SQL variable or table column
' uses a fixed length datatype such as nchar(50).
' If the trailing spaces are not excluded, this function will return 50 which is not
' correct or expected.
myIndex = StringInfo.ParseCombiningCharacters(value.TrimEnd())
If (myIndex IsNot Nothing) Then
Return myIndex.Length
Else
Return 0
End If
End Function
''' <summary>
''' SubS only support character expression of T-SQL funciton SUBSTRING()
''' which returns part of a string.
''' </summary>
''' <param name="value">The input string.</param>
''' <param name="start">The position of the first character that will be returned.</param>
''' <param name="length">The number of characters to return.</param>
''' <returns>The string found at the starting position for the specified
''' number characters.</returns>
<Microsoft.SqlServer.Server.SqlFunction()> _
Public Shared Function SubS(ByVal value As String, ByVal start As Integer, ByVal length As Integer) As String
If value Is Nothing Then
Throw New ArgumentNullException("value")
End If
If length < 0 Then
Throw New ArgumentException("Invalid length parameter passed to the substring function.")
End If
' In Transact-SQL, the substring method initializes to 1. So, start should be initialized to at least 1.
' Length also has to be at least 1 or the Transact-SQL result would be an empty string.
If start + length <= 1 Then
Return String.Empty
End If
' The 2 if statements below guarentee that the result will match the substring function in
' Transact-SQL which will initialize start to 1 by subtracting from the length.
If start <= 0 AndAlso length > 0 Then
length -= 1
End If
If start <= 0 Then
length = length + start
start = 1
End If
Dim myIndex() As Integer
myIndex = StringInfo.ParseCombiningCharacters(value)
Dim NumOfIndexes As Integer
If (myIndex IsNot Nothing) Then
NumOfIndexes = myIndex.Length
Else
NumOfIndexes = 0
End If
start -= 1
If 0 <= start AndAlso start < NumOfIndexes Then
Dim lastIndex As Integer = start + length
' if we are past the last char, then we get the string
' up to the last char
If lastIndex > NumOfIndexes - 1 Then
Return value.Substring(myIndex(start))
Else
Return value.Substring(myIndex(start), myIndex(lastIndex) - myIndex(start))
End If
Else
Return String.Empty
End If
End Function
''' <summary>
''' LeftS is equal to T-SQL string function LEFT() which returns the left
''' part of a character string with the specified number of characters.
''' </summary>
''' <param name="value">The input string.</param>
''' <param name="length">The number of characters to return.</param>
''' <returns>The string found at the starting position for n-length.</returns>
<Microsoft.SqlServer.Server.SqlFunction()> _
Public Shared Function LeftS(ByVal value As String, ByVal length As Integer) As String
If length < 0 Then
Throw New ArgumentException("Length must be a positive integer")
End If
Return SubS(value, 1, length)
End Function
' RightS is equal to T-SQL string function RIGHT() which returns the right
' part of a character string with the specified number of characters.
<Microsoft.SqlServer.Server.SqlFunction()> _
Public Shared Function RightS(ByVal value As String, ByVal length As Integer) As String
If value Is Nothing Then
Throw New ArgumentNullException("value")
End If
If length < 0 Then
Throw New NotSupportedException("Length must be a positive integer")
End If
Dim myIndex() As Integer
myIndex = StringInfo.ParseCombiningCharacters(value)
Dim NumOfIndexes As Integer
If (myIndex IsNot Nothing) Then
NumOfIndexes = myIndex.Length
Else
NumOfIndexes = 0
End If
If NumOfIndexes <= length Then
Return value
End If
If length = 0 Then
Return String.Empty
End If
Dim virtualStartIndex As Integer = NumOfIndexes - length
Dim physicalStartIndex As Integer = myIndex(virtualStartIndex)
Return value.Substring(physicalStartIndex)
End Function
''' <summary>
''' ReplaceS is equal to T-SQL string function REPLACE() which replaces all
''' occurrences of the second given string expression in the first string expression
''' with a third expression.
''' </summary>
''' <param name="value"></param>
''' <param name="replaceValue"></param>
''' <param name="newValue"></param>
''' <returns></returns>
''' <remarks></remarks>
<Microsoft.SqlServer.Server.SqlFunction()> _
Public Shared Function ReplaceS(ByVal value As String, ByVal replaceValue As String, ByVal newValue As String) As String
Dim result As New StringBuilder(value.Length)
Dim myIndex() As Integer
Dim i As Integer = 0
Dim upperValue As String = value.ToUpper(CultureInfo.CurrentUICulture)
Dim upperReplaceValue As String = replaceValue.ToUpper(CultureInfo.CurrentUICulture)
myIndex = StringInfo.ParseCombiningCharacters(upperValue)
While i < value.Length
Dim possibleMatch As Integer = upperValue.IndexOf(upperReplaceValue, i)
If possibleMatch < 0 Then
result.Append(value.Substring(i))
Exit While
Else
'Ensure we're not matching a partial surrogate
Dim surrogateIndex As Integer = Array.IndexOf(Of Integer)(myIndex, possibleMatch)
If surrogateIndex < 0 Then
'We've matched in the middle of a surrogate, skip this match
'as it is not valid.
Dim nextStart As Integer = possibleMatch + 1
result.Append(value.Substring(i, nextStart - i))
i = nextStart
Else
'This is a valid match. Make the substitution.
result.Append(value.Substring(i, possibleMatch - i))
result.Append(newValue)
i = possibleMatch + replaceValue.Length
End If
End If
End While
Return result.ToString()
End Function
End Class
Il s'agit du script d'installation Transact-SQL (Install.sql), qui déploie l'assembly et crée les fonctions sensibles aux caractères supplémentaires dans la base de données.
Use [AdventureWorks]
Go
IF OBJECT_ID('[dbo].[len_s]') IS NOT NULL
DROP FUNCTION [dbo].[len_s];
IF OBJECT_ID('[dbo].[sub_s]') IS NOT NULL
DROP FUNCTION [dbo].[sub_s];
IF OBJECT_ID('[dbo].[left_s]') IS NOT NULL
DROP FUNCTION [dbo].[left_s];
IF OBJECT_ID('[dbo].[right_s]') IS NOT NULL
DROP FUNCTION [dbo].[right_s];
IF OBJECT_ID('[dbo].[replace_s]') IS NOT NULL
DROP FUNCTION [dbo].[replace_s];
GO
IF EXISTS (SELECT [name] FROM sys.assemblies
WHERE [name] = 'SurrogateStringFunction')
DROP ASSEMBLY SurrogateStringFunction;
GO
USE master
GO
IF EXISTS (SELECT * FROM sys.server_principals WHERE [name] = 'ExternalSample_Login')
DROP LOGIN ExternalSample_Login;
GO
IF EXISTS (SELECT * FROM sys.asymmetric_keys WHERE [name] = 'ExternalSample_Key')
DROP ASYMMETRIC KEY ExternalSample_Key;
GO
--Before we register the assembly to SQL Server, we must arrange for the appropriate permissions.
--Assemblies with unsafe or external_access permissions can only be registered and operate correctly
--if either the database trustworthy bit is set or if the assembly is signed with a key,
--that key is registered with SQL Server, a server principal is created from that key,
--and that principal is granted the external access or unsafe assembly permission. We choose
--the latter approach as it is more granular, and therefore safer. You should never
--register an assembly with SQL Server (especially with external_access or unsafe permissions) without
--thoroughly reviewing the source code of the assembly to make sure that its actions
--do not pose an operational or security risk for your site.
DECLARE @SamplesPath nvarchar(1024);
-- You may need to modify the value of the this variable if you have installed the sample someplace other than the default location.
set @SamplesPath = N'C:\MySample\'
EXEC('CREATE ASYMMETRIC KEY ExternalSample_Key FROM EXECUTABLE FILE = ''' + @SamplesPath
+ 'SurrogateStringFunction.dll'';');
CREATE LOGIN ExternalSample_Login FROM ASYMMETRIC KEY ExternalSample_Key
GRANT EXTERNAL ACCESS ASSEMBLY TO ExternalSample_Login;
GO
USE AdventureWorks;
GO
--
-- Create assembly to register class methods for create functions
--
DECLARE @SamplesPath nvarchar(1024);
-- You may need to modify the value of the this variable if you have installed the sample someplace other than the default location.
set @SamplesPath = N'C:\MySample\'
CREATE ASSEMBLY [SurrogateStringFunction]
FROM @SamplesPath + 'SurrogateStringFunction.dll'
WITH PERMISSION_SET = EXTERNAL_ACCESS;
GO
CREATE FUNCTION [dbo].[len_s] (@str nvarchar(4000))
RETURNS bigint
AS EXTERNAL NAME [SurrogateStringFunction].[SurrogateStringFunction].[LenS];
GO
CREATE FUNCTION [dbo].[sub_s](@str nvarchar(4000), @pos int, @cont int)
RETURNS nvarchar(4000)
AS EXTERNAL NAME [SurrogateStringFunction].[SurrogateStringFunction].[SubS];
GO
CREATE FUNCTION [dbo].[left_s](@str nvarchar(4000), @cont int)
RETURNS nvarchar(4000)
AS EXTERNAL NAME [SurrogateStringFunction].[SurrogateStringFunction].[LeftS];
GO
CREATE FUNCTION [dbo].[right_s](@str nvarchar(4000), @cont int)
RETURNS nvarchar(4000)
AS EXTERNAL NAME [SurrogateStringFunction].[SurrogateStringFunction].[RightS];
GO
CREATE FUNCTION [dbo].[replace_s](@str nvarchar(4000), @str1 nvarchar(4000), @str2 nvarchar(4000))
RETURNS nvarchar(4000)
AS EXTERNAL NAME [SurrogateStringFunction].[SurrogateStringFunction].[ReplaceS];
GO
Il s'agit de test.sql, qui teste l'exemple en exécutant les fonctions.
Use [AdventureWorks]
Go
-- left_s VS Left
print ('***** left_s VS Left *****');
select [dbo].[left_s](N'౷౸123',2);
print(N'Should Return ౷౸');
go
select Left(N'౷౸123',2);
print(N'Will Return ౷');
go
-- right_s VS Right
print ('***** right_s VS Right *****')
select [dbo].[right_s](N'౷౸123',5);
print(N'Should Return ౷౸123');
go
select Right(N'౷౸123',5);
print(N'Will Return ౸123');
go
-- len_s VS Len
print('***** len_s VS Len *****');
select [dbo].[len_s](N'ƾǀǃ12');
print(N'Should Return 5');
go
select Len(N'ƾǀǃ12');
print(N'Will Return 8');
go
-- sub_s VS Substring
print('***** sub_s VS Subscription *****');
select [dbo].[sub_s] (N'♢♣♤♥♦♧♨♩♪♫♬♭♮♯♰♱♲♳',3,5);
print(N'Should Return ♤♥♦♧♨');
go
select substring(N'♢♣♤♥♦♧♨♩♪♫♬♭♮♯♰♱♲♳',3,5);
print(N'Will Return ♣♤');
go
-- replace_s VS Replace
print('***** replace_s VS Replace *****');
select [dbo].[replace_s](N'ᥕᥖᥗᥙᥚᥛᥕᥖᥗᥙᥚᥛ',N'ᥗᥙᥚ',N'ᦼ');
print(N'Should Return ᥖᦼᥛᥕᥖᦼᥛ');
go
select replace(N'ᥕᥖᥗᥙᥚᥛᥕᥖᥗᥙᥚᥛ',N'ᥗᥙᥚ',N'ᦼ');
print(N'Will Return ᦼ');
go
Le code Transact-SQL suivant supprime l'assembly et les fonctions de la base de données.
-- Drop assemblies and functions if they exist.
USE [AdventureWorks]
GO
IF OBJECT_ID('[dbo].[len_s]') IS NOT NULL
DROP FUNCTION [dbo].[len_s];
IF OBJECT_ID('[dbo].[sub_s]') IS NOT NULL
DROP FUNCTION [dbo].[sub_s];
IF OBJECT_ID('[dbo].[left_s]') IS NOT NULL
DROP FUNCTION [dbo].[left_s];
IF OBJECT_ID('[dbo].[right_s]') IS NOT NULL
DROP FUNCTION [dbo].[right_s];
IF OBJECT_ID('[dbo].[replace_s]') IS NOT NULL
DROP FUNCTION [dbo].[replace_s];
GO
IF EXISTS (SELECT [name] FROM sys.assemblies
WHERE [name] = 'SurrogateStringFunction')
DROP ASSEMBLY SurrogateStringFunction;
GO
USE master
GO
IF EXISTS (SELECT * FROM sys.server_principals WHERE [name] = 'ExternalSample_Login')
DROP LOGIN ExternalSample_Login;
GO
IF EXISTS (SELECT * FROM sys.asymmetric_keys WHERE [name] = 'ExternalSample_Key')
DROP ASYMMETRIC KEY ExternalSample_Key;
GO
USE [AdventureWorks]
GO
Voir aussi
Concepts
Scénarios et exemples d'utilisation pour l'intégration du CLR (Common Language Runtime)