Execute a DELETE command whilst iterating through an XML input parameter - sql-server

Question

I have a stored procedure that receives 2 parameters.
#username VARCHAR(8),
#xmlShiftDays XML
I want to delete multiple rows from the database while iterating through the XML.
I have managed to do something similar for an INSERT (see below)
INSERT INTO table(username, date)
SELECT
username = #username,
CONVERT(DATETIME,shiftDate.date.value('.','VARCHAR(10)'),103)
FROM
#xmlShiftDays.nodes('/shiftDates/date') as shiftDate(date)
This will successfully insert "x" amount of rows into my table.
I now want to re-engineer the query to DELETE "x" amount of rows. If anyone knows how or could point me in the right direction I would greatly appreciate it.
An example of what I want to achieve is:
DECLARE #username VARCHAR(8)
DECLARE #xmlShiftDays XML
SET #xmlShiftDays = '<shiftDates><date>21/01/2012</date></shiftDates>'
SET #username = 'A0123456'
DELETE FROM table
WHERE username = #username
AND date = "<b>loop through the nodes in the XML string</b>"

Answer 1

Assuming you're using SQL Server 2008 (or newer) for this so I can use the DATE datatype (unfortunately, you didn't specify in your question which version of SQL Server you're using).....
I would strongly recommend you use a language-independent, regional-settings-independent date format in your XML - use the ISO-8601 format of YYYYMMDD for best results.
So try something like this:
DECLARE #xmlShiftDays XML
SET #xmlShiftDays = '<shiftDates><date>20120122</date><date>20120227</date></shiftDates>'
;WITH DatesToDelete AS
(
SELECT
DeletionDate = DT.value('(.)[1]', 'date')
FROM #XmlShiftDays.nodes('/shiftDates/date') AS SD(DT)
)
SELECT * FROM DatesToDelete
This should give you the two dates combined into XML string - right?
Now, you can use this to do the deletion from your table:
DECLARE #username VARCHAR(8)
DECLARE #xmlShiftDays XML
SET #xmlShiftDays = '<shiftDates><date>20120122</date><date>20120227</date></shiftDates>'
SET #username = 'A0123456'
;WITH DatesToDelete AS
(
SELECT
DeletionDate = DT.value('(.)[1]', 'date')
FROM #XmlShiftDays.nodes('/shiftDates/date') AS SD(DT)
)
DELETE FROM dbo.Table
WHERE username = #username
AND date IN (SELECT DeletionDate FROM DatesToDelete)
Does that work for you?

Answer 2

You can select the date from the Xml in the same way you did for the Insert:
DELETE FROM table
WHERE username = #username
AND date IN (SELECT
CONVERT(DATETIME,shiftDate.date.value('.','VARCHAR(10)'),103)
FROM
#xmlShiftDays.nodes('/shiftDates/date') as shiftDate(date))