SQL Server table to nested xml file - sql

Question

I have a table like this:
Action Action2 Name Action3 Batch
--------------------------------------
add PL Steve add 1
add PL Steve add 3
add PL Steve add 4
add PL Steve add 5
add PL Steve add 1
add PL Steve add 3
add PL Steve add 4
add PL Steve add 5
and need to turn it into an XML document like this:

Answer 1

Thanks #Isaac for the data script!
for <List> elements in <Branch> node, like <Branch><List/><List/></Branch>:
CREATE TABLE #mytable
(
Action VARCHAR(10),
Action2 VARCHAR(10),
Name VARCHAR(50),
Action3 VARCHAR(10),
Batch INT
);
INSERT INTO #mytable(Action,Action2,Name,Action3,Batch)
VALUES
('add','PL','Steve','add',1),
('add','PL','Steve','add',3),
('add','PL','Steve','add',4),
('add','PL','Steve','add',5),
('add','PL','Steve','add',1),
('add','PL','Steve','add',3),
('add','PL','Steve','add',4),
('add','PL','Steve','add',5);
INSERT INTO #mytable(Action,Action2,Name,Action3,Batch)
VALUES
('update','PL','John','insert',5),
('update','PL','Paul','insert',1),
('update','PL','Chris','delete',3),
('update','PL','Mary','update',4),
('update','PL','Jane','delete',5);
select a1.Action as '#Action', s.brancexml as '*'
from
(
select distinct Action
from #mytable
) as a1
cross apply
(
select
(
select a2.Action2 AS '#Action', a2.Name as '#Name', x.listxml as '*'
from
(
select distinct Action2, Name
from #mytable AS b
where b.Action = a1.Action
) AS a2
cross apply
(
select
(
select distinct c.Action3 as '#Action', c.Batch as '#Batch'
from #mytable AS c
where c.Action = a1.Action AND c.Action2 = a2.Action2 AND c.Name = a2.Name
for xml path('List'), type
) AS listxml
) as x
for xml path('Brance'), type
) as brancexml
) as s
for xml path('Start'), root('Entries'), type

Answer 2

You've got a solution already, but this might be put a bit simpler:
CREATE TABLE #mytable
(
Action VARCHAR(10),
Action2 VARCHAR(10),
Name VARCHAR(50),
Action3 VARCHAR(10),
Batch INT
);
INSERT INTO #mytable(Action,Action2,Name,Action3,Batch)
VALUES
('add','PL','Steve','add',1),
('add','PL','Steve','add',3),
('add','PL','Steve','add',4),
('add','PL','Steve','add',5),
('update','PL','John','insert',5),
('update','PL','Paul','insert',1),
('update','PL','Chris','delete',3),
('update','PL','Mary','update',4),
('update','PL','Jane','delete',5);
SELECT mt1.[Action] AS [#Action]
,(
SELECT mt2.Action2 AS [#Action]
,mt2.[Name] AS [#Name]
,(
SELECT mt3.Action3 AS [#Action]
,mt3.Batch AS [#Batch]
FROM #mytable mt3
WHERE mt3.[Action]=mt1.[Action]
AND mt3.Action2=mt2.Action2
AND mt3.[Name]=mt2.[Name]
FOR XML PATH('List'),TYPE
)
FROM #mytable mt2
WHERE mt2.[Action]=mt1.[Action]
GROUP BY mt2.Action2,mt2.[Name]
FOR XML PATH('Brance'),TYPE
)
FROM #mytable mt1
GROUP BY mt1.[Action]
FOR XML PATH('Start'),ROOT('Entries');
The idea in short:
We use a cascade of correlated sub-queries, each returning one fragment of the nested structure.
Using ,TYPE will return this as XML, otherwise you would get escaped text.
Using GROUP BY allows us to return the nesting data just once.
This won't be very fast... Indexes on the columns used in WHERE will help you.