SELECT FULLNAME From UserInfo

SELECT Last, First, MI from UserInfo

create FUNCTION dbo.f_parseName(@inFullName varchar(255))
RETURNS
    @tbl TABLE (lastName varchar(255), firstName varchar(255), middleName varchar(255))
as
BEGIN
-- put your logic here
insert into @tbl(lastName,firstName,middleName)
select substring(@inFullName,0,10),substring(@inFullName,11,10), substring(@inFullName,21,10)

return

end

-- sample data
declare @fullNames table (fullName varchar(255))
insert into @fullNames (fullName) values
('111111111122222222223333333333')
,('AAAAAAAAAABBBBBBBBBBCCCCCCCCCC')


select
    fn.fullName
    ,pn.lastName
    ,pn.firstName
    ,pn.middleName
from
    @fullNames fn
    cross apply dbo.f_parseName(fn.fullName) pn

alter table UserInfo
    add firstName as SUBSTRING(fullName, CHARINDEX(',',fullName,0)+2, LEN(fullName)-CHARINDEX(',',fullName,0)-CHARINDEX(' ', REVERSE(fullName),0)-1)
        ,lastName as SUBSTRING(fullName, 0, CHARINDEX(',',fullName,0))
        ,middleInitital as REVERSE(SUBSTRING(REVERSE(fullName),0,CHARINDEX(' ', REVERSE(fullName),0)))

select  firstName
        ,lastName
        ,middleInitital
from UserInfo

CREATE TABLE #temp (
  FULLNAME NVARCHAR(..)
  ,Last NVARCHAR(..)
  ,First NVARCHAR(..)
  ,MI NVARCHAR(..)
);

INSERT INTO #temp (Last, First, MI)
EXECUTE MySproc;

UPDATE NUI
  SET NUI.Last = T.Last, NUI.First = T.First, NUI.MI = T.MI
  FROM NewUserInfo AS NUI
  INNER JOIN #temp AS T ON NUI.FULLNAME = T.FULLNAME;