Ejemplo de manipulación de cadenas que detectan caracteres complementarios

Artículo
05/08/2013

Este ejemplo para SQL Server muestra el procesamiento de cadenas de caracteres complementarios. En este ejemplo se muestra la implementación de cinco funciones de cadena de Transact-SQL que proporcionan las mismas funciones de manipulación de cadenas que las funciones integradas, pero con una función adicional que reconoce caracteres complementarios para controlar cadenas de caracteres Unicode y complementarios. Las cinco funciones son lens(), lefts(), rights(), subs() y replace_s() que son equivalentes a las funciones integradas LEN(), LEFT(), RIGHT(), SUBSTRING() y las funciones de cadena REPLACE().

Requisitos previos

Para crear y ejecutar este proyecto se debe instalar el siguiente software:

SQL Server o SQL Server Express. Puede obtener SQL Server Express de forma gratuita desde el sitio web de documentación y ejemplos de SQL Server Express.
La base de datos AdventureWorks que está disponible en el sitio web para desarrolladores de SQL Server.
.NET Framework SDK 2.0 o posterior, o Microsoft Visual Studio 2005 o posterior. Puede obtener .NET Framework SDK de forma gratuita.
Además, se deben cumplir las siguientes condiciones:
La instancia de SQL Server que está utilizando debe tener habilitada la integración con CLR.
Para habilitar la integración con CLR, siga estos pasos:

Habilitar la integración con CLR
- Ejecute los siguientes comandos Transact-SQL:
sp_configure 'clr enabled', 1

GO

RECONFIGURE

GO

[!NOTA]

Para habilitar CLR, debe tener el permiso de nivel de servidor ALTER SETTINGS, que se concede implícitamente a los miembros de los roles fijos de servidor sysadmin y serveradmin.
La base de datos AdventureWorks debe estar instalada en la instancia de SQL Server que está utilizando.
Si no es administrador de la instancia de SQL Server que utiliza, debe hacer que un administrador le conceda el permiso CreateAssembly para completar la instalación.

Generar el ejemplo

Cree y ejecute el ejemplo utilizando las siguientes instrucciones:

Abra un símbolo del sistema de Visual Studio o de .NET Framework.
Si es necesario, cree un directorio para el ejemplo. Para este ejemplo, utilizaremos C:\MySample.
Como este ejemplo requiere un ensamblado firmado, cree una clave asimétrica escribiendo el comando:

sn -k SampleKey.snk
Compile el código muestra desde el símbolo del sistema ejecutando uno de los comandos siguientes, dependiendo de su opción de lenguaje.
- 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
Copie el código de instalación de Transact-SQL en un archivo y guárdelo como Install.sql en el directorio de ejemplo.
Implemente el ensamblado y el procedimiento almacenado ejecutando
- sqlcmd -E -I -i install.sql -v root = "C:\MySample\"
Copie el script de comando de prueba de Transact-SQL en un archivo y guárdelo como test.sql en el directorio de ejemplo.
Ejecute el script de prueba con el siguiente comando
- sqlcmd -E -I -i test.sql
Copie el script de limpieza de Transact-SQL en un archivo y guárdelo como cleanup.sql en el directorio de ejemplo.
Ejecute el script con el siguiente comando
- sqlcmd -E -I -i cleanup.sql

Código muestra

A continuación se muestran las listas de código para este ejemplo.

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

Este es el script de instalación de Transact-SQL (Install.sql) que implementa el ensamblado y crea las funciones que detectan caracteres complementarios en la base de datos.

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

Este es el script test.sql que prueba el ejemplo ejecutando las funciones.

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

El siguiente script Transact-SQL quita de la base de datos el ensamblado y las funciones.

-- 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

Vea también

Conceptos

Escenarios de uso y ejemplos para la integración de Common Language Runtime (CLR)

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