Levenshtein distance in T-SQL

Question

I am interested in algorithm in T-SQL calculating Levenshtein distance.

Answer 1

IIRC, with SQL Server 2005 and later you can write stored procedures in any .NET language: Using CLR Integration in SQL Server 2005. With that it shouldn't be hard to write a procedure for calculating Levenstein distance.

A simple Hello, World! extracted from the help:

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

public class HelloWorldProc
{
    [Microsoft.SqlServer.Server.SqlProcedure]
    public static void HelloWorld(out string text)
    {
        SqlContext.Pipe.Send("Hello world!" + Environment.NewLine);
        text = "Hello world!";
    }
}

Then in your SQL Server run the following:

CREATE ASSEMBLY helloworld from 'c:\helloworld.dll' WITH PERMISSION_SET = SAFE

CREATE PROCEDURE hello
@i nchar(25) OUTPUT
AS
EXTERNAL NAME helloworld.HelloWorldProc.HelloWorld

And now you can test run it:

DECLARE @J nchar(25)
EXEC hello @J out
PRINT @J

Hope this helps.