Come codificare caratteri specifici della lingua durante la conversione di varbinary() in varchar(max) in SQL Server 2012?

In generale, SQL Server non tiene in grande considerazione UTF-8. Tuttavia, .NET ha metodi per farlo e puoi ottenerli tramite l'integrazione CLR.

Compilalo usando C#:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;

namespace UtfLib
{
    public static class UtfMethods
    {
        [SqlFunction(IsDeterministic = true, IsPrecise = true)]
        public static SqlBinary NVarCharToUtf8(SqlString inputText)
        {
            if (inputText.IsNull)
                return new SqlBinary(); // (null)

            return new SqlBinary(Encoding.UTF8.GetBytes(inputText.Value));
        }

        [SqlFunction(IsDeterministic = true, IsPrecise = true)]
        public static SqlString Utf8ToNVarChar(SqlBinary inputBytes)
        {
            if (inputBytes.IsNull)
                return new SqlString(); // (null)

            return new SqlString(Encoding.UTF8.GetString(inputBytes.Value));
        }
    }
}

Importa l'assieme nel tuo database e crea le funzioni esterne:

CREATE ASSEMBLY UtfLib
FROM 'C:\UtfLib.dll'
GO
CREATE FUNCTION NVarCharToUtf8 (@InputText NVARCHAR(MAX))
RETURNS VARBINARY(MAX)
AS EXTERNAL NAME UtfLib.[UtfLib.UtfMethods].NVarCharToUtf8
GO
CREATE FUNCTION Utf8ToNVarChar (@InputBytes VARBINARY(MAX))
RETURNS NVARCHAR(MAX)
AS EXTERNAL NAME UtfLib.[UtfLib.UtfMethods].Utf8ToNVarChar

Ultimo passaggio, devi abilitare clr

sp_configure 'clr enabled',1
GO
RECONFIGURE
GO
sp_configure 'clr enabled'  -- make sure it took
GO

e voilà!

SELECT dbo.Utf8ToNVarChar(DATA) FROM [dbo].[TABLE_NAME]