to find the SQL Port nunber by t-sql from registries

DECLARE @InstanceName nvarchar(50)
DECLARE @value VARCHAR(100)
DECLARE @RegKey_InstanceName nvarchar(500)
DECLARE @RegKey nvarchar(500)

SET @InstanceName=CONVERT(nVARCHAR,isnull(SERVERPROPERTY('INSTANCENAME'),'MSSQLSERVER'))

--For SQL Server 2000
if(SELECT Convert(varchar(1),(SERVERPROPERTY('ProductVersion'))))=8
BEGIN
if @InstanceName='MSSQLSERVER'
Begin
SET @RegKey='SOFTWARE\Microsoft\'+@InstanceName+'\MSSQLServer\SuperSocketNetLib\TCP\'
END
ELSE
BEGIN
SET @RegKey='SOFTWARE\Microsoft\Microsoft SQL Server\'+@InstanceName+'\MSSQLServer\SuperSocketNetLib\TCP\'
END

EXECUTE xp_regread
@rootkey = 'HKEY_LOCAL_MACHINE',
@key = @RegKey,
@value_name = 'TcpPort',
@value = @value OUTPUT

Select @@SERVERNAME as ServerName,@value as PortNumber
END


--For SQL Server 2005 and up
if(SELECT Convert(varchar(1),(SERVERPROPERTY('ProductVersion'))))<>8
BEGIN
SET @RegKey_InstanceName='SOFTWARE\Microsoft\Microsoft SQL Server\Instance Names\SQL'


EXECUTE xp_regread
@rootkey = 'HKEY_LOCAL_MACHINE',
@key = @RegKey_InstanceName,
@value_name = @InstanceName,
@value = @value OUTPUT
SET @RegKey='SOFTWARE\Microsoft\Microsoft SQL Server\'+@value+'\MSSQLServer\SuperSocketNetLib\TCP\IPAll'

EXECUTE xp_regread
@rootkey = 'HKEY_LOCAL_MACHINE',
@key = @RegKey,
@value_name = 'TcpPort',
@value = @value OUTPUT

Select @@SERVERNAME as ServerName,@value as PortNumber
END