Esempio di manipolazione di stringhe Supplementary-Aware

Questo esempio per SQL Server illustra l'elaborazione di stringhe con riconoscimento dei caratteri supplementari. In questo esempio viene illustrata l'implementazione di cinque funzioni stringa Transact-SQL che forniscono le stesse funzioni di manipolazione delle stringhe delle funzioni predefinite, ma con funzionalità aggiuntive in grado di gestire sia stringhe di caratteri Unicode che supplementari. Le cinque funzioni sono lens() lefts(), rights(), subs() e replace_s() equivalenti alle funzioni LEN(), LEFT(), RIGHT(), SUBSTRING() predefinite e REPLACE() alle funzioni stringa.

Prerequisiti

Per creare ed eseguire questo progetto, è necessario installare il software seguente:

SQL Server o SQL Server Express. È possibile ottenere gratuitamente SQL Server Express dalla documentazione di SQL Server Express e dal sito Web degli esempi
Database AdventureWorks disponibile nel sito Web per sviluppatori di SQL Server
.NET Framework SDK 2.0 o versione successiva o Microsoft Visual Studio 2005 o versione successiva. È possibile ottenere gratuitamente .NET Framework SDK.
Inoltre, devono essere soddisfatte le condizioni seguenti:
L'istanza di SQL Server in uso deve avere l'integrazione CLR abilitata.
Per abilitare l'integrazione con CLR, seguire questa procedura:

Abilitazione dell'integrazione con CLR
- Eseguire i comandi di Transact-SQL seguenti:
sp_configure 'clr enabled', 1

GO

RECONFIGURE

GO

Annotazioni

Per abilitare CLR, è necessario disporre ALTER SETTINGS dell'autorizzazione a livello di server, che viene mantenuta in modo implicito dai membri dei ruoli predefiniti del sysadmin server e serveradmin .
Il database AdventureWorks deve essere installato nell'istanza di SQL Server in uso.
Se non si è un amministratore per l'istanza di SQL Server in uso, è necessario disporre di un amministratore che conceda l'autorizzazione CreateAssembly per completare l'installazione.

Compilazione dell'esempio

Creare ed eseguire l'esempio usando le istruzioni seguenti:

Aprire un prompt dei comandi di Visual Studio o .NET Framework.
Se necessario, creare una directory per l'esempio. Per questo esempio si userà C:\MySample.
Poiché questo esempio richiede un assembly firmato, creare una chiave asimmetrica digitando il comando :

sn -k SampleKey.snk
Compilare il codice di esempio dal prompt della riga di comando eseguendo una delle opzioni seguenti, a seconda del linguaggio scelto.
- 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
Copiare il codice di installazione Transact-SQL in un file e salvarlo come Install.sql nella directory di esempio.
Distribuire l'assembly e la stored procedure eseguendo
- sqlcmd -E -I -i install.sql -v root = "C:\MySample\"
Copiare Transact-SQL script del comando di test in un file e salvarlo come test.sql nella directory di esempio.
Eseguire lo script di test con il comando seguente
- sqlcmd -E -I -i test.sql
Copiare lo script di pulizia Transact-SQL in un file e salvarlo come cleanup.sql nella directory di esempio.
Eseguire lo script con il comando seguente
- sqlcmd -E -I -i cleanup.sql

Codice di esempio

Di seguito sono riportati gli elenchi di codice per questo esempio.

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 guarantee 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 guarantee 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

Si tratta dello script di installazione Transact-SQL (Install.sql), che distribuisce l'assembly e crea le funzioni con riconoscimento supplementare nel database.

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

Si tratta di test.sql, che testa l'esempio eseguendo le funzioni.

Use [AdventureWorks]  
Go  
  
-- left_s  VS  Left  
print ('***** left_s VS Left *****');  
select [dbo].[left_s](N'𠱷𠱸123',2);  
print(N'Should Return 𠱷𠱸');  
go  
select Left(N'𠱷𠱸123',2);  
print(N'Will Return 𠱷');  
go  
  
-- right_s VS Right  
print ('***** right_s VS Right *****')  
select [dbo].[right_s](N'𠱷𠱸123',5);  
print(N'Should Return 𠱷𠱸123');  
go  
select Right(N'𠱷𠱸123',5);  
print(N'Will Return 𠱸123');  
go  
  
-- len_s  VS Len  
print('***** len_s VS Len *****');  
select [dbo].[len_s](N'𠆾𠇀𠇃12');  
print(N'Should Return 5');  
go  
select Len(N'𠆾𠇀𠇃12');  
print(N'Will Return 8');  
go  
  
-- sub_s VS Substring  
print('***** sub_s VS Subscription *****');  
select [dbo].[sub_s] (N'𢙢𢙣𢙤𢙥𢙦𢙧𢙨𢙩𢙪𢙫𢙬𢙭𢙮𢙯𢙰𢙱𢙲𢙳',3,5);  
print(N'Should Return 𢙤𢙥𢙦𢙧𢙨');  
go  
select substring(N'𢙢𢙣𢙤𢙥𢙦𢙧𢙨𢙩𢙪𢙫𢙬𢙭𢙮𢙯𢙰𢙱𢙲𢙳',3,5);  
print(N'Will Return 𢙣𢙤');  
go  
  
-- replace_s VS Replace  
print('***** replace_s VS Replace *****');  
select [dbo].[replace_s](N'𡥕𡥖𡥗𡥙𡥚𡥛𡥕𡥖𡥗𡥙𡥚𡥛',N'𡥗𡥙𡥚',N'𡦼');  
print(N'Should Return 𡥖𡦼𡥛𡥕𡥖𡦼𡥛');  
go  
select replace(N'𡥕𡥖𡥗𡥙𡥚𡥛𡥕𡥖𡥗𡥙𡥚𡥛',N'𡥗𡥙𡥚',N'𡦼');  
print(N'Will Return 𡦼');  
go

L'Transact-SQL seguente rimuove l'assembly e le funzioni dal database.

-- 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

Vedere anche

Scenari di utilizzo ed esempi per l'integrazione con CLR (Common Language Runtime)

Last updated on 2017-06-13

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