SqlServer-NVARCHAR(32)转Guid

IF OBJECT_ID('ToGuid','FN') IS NOT NULL
BEGIN
DROP FUNCTION ToGuid;
END
GO
CREATE FUNCTION ToGuid(@str NVARCHAR(32))
RETURNS UNIQUEIDENTIFIER
AS
BEGIN
--DECLARE @result UNIQUEIDENTIFIER
SET @str = ISNULL(@str, '');
IF LEN(@str)<32 BEGIN RETURN ''; END
--SET @result=CAST(LEFT(@str, 8) + '-' + SUBSTRING(@str, 9, 4) + '-' + SUBSTRING(@str, 13, 4) +
-- '-' + SUBSTRING(@str, 17, 4) + '-' + SUBSTRING(@str, 21, 12) AS UNIQUEIDENTIFIER);
return LEFT(@str, 8) + '-' + SUBSTRING(@str, 9, 4) + '-' + SUBSTRING(@str, 13, 4) +
'-' + SUBSTRING(@str, 17, 4) + '-' + SUBSTRING(@str, 21, 12);
END
GO