Exemplo de manipulação de cadeias de caracteres com reconhecimento de suplementares
Este exemplo para SQL Server demonstra o processamento de cadeia de caracteres com reconhecimento de caractere suplementar. Este exemplo mostra a implementação de cinco funções da cadeia de caracteres do Transact-SQL que fornecem as mesmas funções de manipulação de cadeia de caracteres, como as funções internas, porém com capacidade de reconhecimento de caracteres suplementares adicionais para tratar cadeias de caracteres suplementares e Unicode. As cinco funções são lens() lefts(), rights(), subs() e replace_s() que são equivalentes às funções internas LEN(), LEFT(), RIGHT(), SUBSTRING() e REPLACE() às funções de cadeia de caracteres.
Pré-requisitos
Para criar e executar este projeto, o software a seguir deve estar instalado:
SQL Server ou SQL Server Express. Você pode obter SQL Server Express gratuitamente no site de Documentação e Exemplos do SQL Server Express
O banco de dados AdventureWorks que está disponível no site do SQL Server Developer
.NET Framework SDK 2.0 ou posterior ou Microsoft Visual Studio 2005 ou posterior. Você pode obter o .NET Framework SDK gratuitamente.
Além disso, as seguintes condições devem ser atendidas:
A instância SQL Server que você está usando deve ter a integração CLR habilitada.
Para habilitar a integração CLR, execute as etapas a seguir:
Habilitando integração CLR
- Execute os seguintes comandos Transact-SQL:
sp_configure 'clr enabled', 1GORECONFIGUREGOObservação
Para habilitar o CLR, é necessário ter a permissão
ALTER SETTINGSde nível de servidor, que é mantida implicitamente por membros das funções de servidor fixassysadmineserveradmin.O banco de dados AdventureWorks deve ser instalado na instância SQL Server que você está usando.
Se você não for um administrador da instância de SQL Server que está usando, deverá ter uma permissão CreateAssembly concedida ao administrador para concluir a instalação.
Compilando o exemplo
Crie e execute o exemplo seguindo estas instruções:
Abra um prompt de comando do Visual Studio ou do .NET Framework.
Se necessário, crie um diretório para o seu exemplo. Para este exemplo, usaremos C:\MySample.
Como este exemplo exige um assembly assinado, crie uma chave assimétrica digitando o comando:
sn -k SampleKey.snkCompile o código de exemplo no prompt de linha de comando executando uma das seguintes ações, de acordo com sua opção de linguagem.
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.vbCsc /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
Copie o código de instalação do Transact-SQL em um arquivo e salve-o como
Install.sqlno diretório de exemplo.Implante o assembly e o procedimento armazenado executando o seguinte
sqlcmd -E -I -i install.sql -v root = "C:\MySample\"
Copie o script de comando de teste do Transact-SQL em um arquivo e salve-o como
test.sqlno diretório de exemplo.Execute o script de teste com o seguinte comando
sqlcmd -E -I -i test.sql
Copie o script de limpeza Transact-SQL em um arquivo e salve-o como
cleanup.sqlno diretório de exemplo.Execute o script com o seguinte comando
sqlcmd -E -I -i cleanup.sql
Exemplo de código
As listagens de código deste exemplo são as seguintes.
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 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
Esse é o script de instalação transact-SQL (Install.sql), que implanta o assembly e cria as funções com reconhecimento suplementar no banco de dados.
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
Esse é o test.sql, que testa o exemplo por meio da execução das funções.
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
O Transact-SQL a seguir remove o assembly e as funções do banco de dados.
-- 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
Consulte Também
Cenários de uso e exemplos para a integração de CLR (Common Language Runtime)