Door komma's gescheiden tekenreeks converteren naar meerdere kolommen in sql-server

Je kunt dit zien werken op SQL Fiddle:http://sqlfiddle.com/#!3/ 8c3ee/32

Hier is het vlees van:

with parsed as (
  select
  commasepa,
  root.value('(/root/s/col[@name="X"])[1]', 'varchar(20)') as X,
  root.value('(/root/s/col[@name="Y"])[1]', 'varchar(20)') as Y,
  root.value('(/root/s/col[@name="Z"])[1]', 'varchar(20)') as Z,
  root.value('(/root/s/col[@name="A"])[1]', 'varchar(20)') as A,
  root.value('(/root/s/col[@name="B"])[1]', 'varchar(20)') as B,
  root.value('(/root/s/col[@name="C"])[1]', 'varchar(20)') as C,
  root.value('(/root/s/col[@name="D"])[1]', 'varchar(20)') as D
FROM
(
select
   commasepa,
   CONVERT(xml,'<root><s><col name="' + REPLACE(REPLACE(COMMASEPA, '=', '">'),',','</col></s><s><col name="') + '</col></s></root>') as root
FROM
  samp
) xml
)
update 
  samp
  set
  samp.x = parsed.x,
  samp.y = parsed.y,
  samp.z = parsed.z,
  samp.a = parsed.a,
  samp.b = parsed.b,
  samp.c = parsed.c,
  samp.d = parsed.d
from
  parsed
where
  parsed.commasepa = samp.commasepa;

Volledige openbaarmaking - ik ben de auteur van sqlfiddle.com

Dit werkt door eerst elke commasepa-tekenreeks te converteren naar een XML-object dat er als volgt uitziet:

<root>
 <s>
  <col name="X">1</col>
 </s>
 <s>
  <col name="Y">2</col>
 </s>
  ....
</root>

Zodra ik de string in die indeling heb, gebruik ik de xquery-opties die SQL Server 2005 (en hoger) ondersteunen, namelijk de .value('(/root/s/col[@name="X"])[1]', 'varchar(20)') een deel. Ik selecteer elk van de potentiële kolommen afzonderlijk, zodat ze worden genormaliseerd en ingevuld indien beschikbaar. Met dat genormaliseerde formaat definieer ik de resultatenset met een Common Table Expression (CTE) die ik 'parsed' noemde. Deze CTE wordt vervolgens weer samengevoegd in de update-instructie, zodat de waarden in de oorspronkelijke tabel kunnen worden ingevuld.