Call stored procedure for each XML element without cursors - sql-server

Question

I have this stored procedure in SQL Server:
alter PROCEDURE [dbo].[spSendLogLinesAsXML]
(
#device_id varchar(128),
#application_name VARCHAR(64),
#application_user_name VARCHAR(6),
#log_lines_xml XML
)
AS
BEGIN
DECLARE
#ixml INT,
#log_line_dt DATETIME,
#log_line_message varchar(max)
EXEC sp_xml_preparedocument #ixml OUTPUT,
#log_lines_xml
SELECT #log_line_dt = dt,
#log_line_message = data
FROM OPENXML(#ixml, '/lines/line', 3) WITH (
dt DATETIME,
data varchar(max)
)
--I want to do the following for each line element
EXEC spSendLogLine
#device_id = #device_id,
#application_name = #application_name,
#application_user_name = #application_user_name,
#log_line_dt = #log_line_dt,
#log_line_message = #log_line_message
EXEC sp_xml_removedocument #ixml
return -100
END
I call the stored procedure like this:
EXEC #return_value = [dbo].[spSendLogLinesAsXML]
#device_id = N'devid123',
#application_name = N'CJA App 1',
#application_user_name = N'anatoli',
#log_lines_xml = '<lines><line><dt>2013-03-01T13:00:00</dt><data>Something happened and it was logged</data></line><line><dt>2013-03-01T13:01:00</dt><data>Oh my god the building is burning and people are dying</data></line></lines>'
How can I modify my stored procedure to call spSendLogLine for each line element?
Edit: According to SQL - Call Stored Procedure for each record cursors are bad. So I want to know a better way. I don't mind how much my stored procedure is changed to achieve this, as long as it ends up working properly and is nice.

Answer 1

alter PROCEDURE [dbo].[spSendLogLinesAsXML]
(
#device_id varchar(128),
#application_name VARCHAR(64),
#application_user_name VARCHAR(6),
#log_lines_xml XML
)
AS
BEGIN
declare #log_line_dt datetime,
#log_line_message varchar(1024)
declare #curse cursor
set #curse = cursor fast_forward for
select n.d.value('dt[1]', 'datetime') as log_line_dt, n.d.value('data[1]', 'varchar(1024)') as log_line_message
from #log_lines_xml.nodes('/lines/line') n(d)
open #curse
fetch next from #curse into #log_line_dt, #log_line_message
while (##fetch_status = 0)
begin
EXEC spSendLogLine
#device_id = #device_id,
#application_name = #application_name,
#application_user_name = #application_user_name,
#log_line_dt = #log_line_dt,
#log_line_message = #log_line_message
fetch next from #curse into #log_line_dt, #log_line_message
end
close #curse;
return -100
END
GO

Answer 2

This is what I ended up with, following muhmud's answer. Still wish someone would tell me how to do it sans cursors.
ALTER PROCEDURE [dbo].[spSendLogLinesAsXML]
(
#device_id VARCHAR(128),
#application_name VARCHAR(64),
#application_user_name VARCHAR(6),
#log_lines_xml XML
)
AS
BEGIN
DECLARE #ixml INT,
#log_line_dt DATETIME,
#log_line_message VARCHAR(max),
#cursor CURSOR
SET #cursor = CURSOR FAST_FORWARD
FOR
SELECT n.d.value('dt[1]', 'datetime') AS log_line_dt,
n.d.value('data[1]', 'varchar(max)') AS log_line_message
FROM #log_lines_xml.nodes('/lines/line') n(d)
OPEN #cursor
FETCH NEXT
FROM #cursor
INTO #log_line_dt,
#log_line_message
WHILE (##fetch_status = 0)
BEGIN
EXEC spSendLogLine #device_id = #device_id,
#application_name = #application_name,
#application_user_name = #application_user_name,
#log_line_dt = #log_line_dt,
#log_line_message = #log_line_message
FETCH NEXT
FROM #cursor
INTO #log_line_dt,
#log_line_message
END
RETURN - 100
END

Answer 3

If you're using SQL Server 2008 or newer, you could do something like this:
define a user-defined table type that holds all the columns that are relevant to your procedure:
CREATE TYPE dbo.SendLogLineType
AS TABLE (LineDate DATETIME2(3), LineData VARCHAR(200), DeviceID VARCHAR(128),
ApplicationName VARCHAR(64), AppUserName VARCHAR(6) )
then, extract your lines into that table, and add the other "fixed" parameters (this happens inside your [spSendLogLinesAsXML] procedure):
DECLARE #InputTable dbo.SendLogLineType
INSERT INTO #InputTable(LineDate, LineData, DeviceID, ApplicationName, AppUserName)
SELECT
XLine.value('(dt)[1]', 'DATETIME2'),
XLine.value('(data)[1]', 'varchar(200)'),
#device_id,
#application_name,
#application_user_name
FROM
#log_lines_xml.nodes('/lines/line') AS XTbl(XLine)
and lastly, change your spSendLogLine procedure to accept a table valued parameter of that defined table type and change its logic so that it will iterate over all rows that get passed into it:
CREATE PROCEDURE spSendLogLine
(#SendLogLineData dbo.SendLogLineType READONLY)
AS
BEGIN
-- iterate over all rows in #SendLogLineData and send out those e-mails!
END
Read more about Table-Valued Parameters on the relevant MSDN SQL Server Books Online documentation page