SQL Server - obtener como filas individuales resultados que están almacenados en una columna como valores separad

-- drop table #Testdata

create table #Testdata(Data varchar(max))

insert #Testdata select  'Sergio,Juan'

insert #Testdata select  'Roberto,Mario,Sergio'

insert #Testdata select  'Juan,Ignacio,Sergio,Mario'

;with tmp (DataItem, Data) as (

select LEFT(Data, CHARINDEX(',',Data+',')-1),

    STUFF(Data, 1, CHARINDEX(',',Data+','), '')

from #Testdata

union all

select LEFT(Data, CHARINDEX(',',Data+',')-1),

    STUFF(Data, 1, CHARINDEX(',',Data+','), '')

from tmp

where Data > ''

)

select  distinct DataItem

from tmp

with tmp (DataItem, copiamail) as (

select LEFT(copiamail, CHARINDEX(',',copiamail+',')-1),

    STUFF(copiamail, 1, CHARINDEX(',',copiamail+','), '')

from informes_dbf

union all

select LEFT(copiamail, CHARINDEX(',',copiamail+',')-1),

    STUFF(copiamail, 1, CHARINDEX(',',copiamail+','), '')

from tmp

where copiamail > ''

)

select  distinct DataItem

from tmp

with tmp (DataItem, copiamail) as (

select LEFT(copiamail, CHARINDEX(',',copiamail+',')-1),

    STUFF(copiamail, 1, CHARINDEX(',',copiamail+','), '')

from informes_dbf

union all

select LEFT(copiamail, CHARINDEX(',',copiamail+',')-1),

    STUFF(copiamail, 1, CHARINDEX(',',copiamail+','), '')

from tmp

where copiamail > ''

)

select  distinct DataItem

from tmp

with tmp (DataItem, copiamail) as (

select cast(LLEFT(copiamail, CHARINDEX(',',copiamail+',')-1) as nvarchar(255)),

    STUFF(copiamail, 1, CHARINDEX(',',copiamail+','), '')

from informes_dbf

union all

select cast(LEFT(copiamail, CHARINDEX(',',copiamail+',')-1) as nvarchar(255)),

    STUFF(copiamail, 1, CHARINDEX(',',copiamail+','), '')

from tmp

where copiamail > ''

)

select  distinct DataItem

from tmp