Question

I’m attempting to create a small console app in C# to perform inserts on a table of Products (ITEMS) in SQL Server 2008 according to the contents of an XML file in the FASTEST way possible. I already have an .XSD file that contains the proper mappings to the SQL table (which may not be necessary with the approach outlined below).

Here’s a high-level of my approach:

1. Read the XML, using it to create a table.
2. Perform a MERGE against the ITEMS table using the table created from the XML file.
   2a. If the item exists, update it.
   2b. If the item does not exist, insert it.
3. Create a log of only the records inserted in XML.

Consider the following ITEMS table and XML file:

ITEMS

  Item_Id    Name    Price  
     1       Coke     5.00  
     2       Pepsi    3.00  
     3       Sprite   2.00   

ITEMS.XML

   <?xml version="1.0" encoding="ISO-8859-1"?>
   <Item>
    <Id>5</Id>
    <Name>Mountain Dew</Name>
    <Price>4.50</Price>
   </Item>
   <Item>
    <Id>3</Id>
    <Name>Sprite Zero</Name>
    <Price>1.75</Price>
   </Item>

After the import, the ITEMS table should look like:

ITEMS

  Item_Id    Name         Price  
     1       Coke          5.00  
     2       Pepsi         3.00  
     3       Sprite Zero   1.75  
     5       Mountain Dew  4.50

Once that’s done, I also need to generate an XML formatted log file that contains the “new” record that was inserted into the table (ITEMS_LOG.XML):

ITEMS_LOG.XML

   <?xml version="1.0" encoding="ISO-8859-1"?>
   <Item>
    <Id>5</Id>
    <Name>Mountain Dew</Name>
    <Price>4.50</Price>
   </Item>

I have tried implementing this using SQLXMLBulkLoad, but unfortunately it does not provide the logging that I need, nor does it permit me to access any of the messages returned from SQL Server (i.e. what’s been inserted/updated). Although I have an intermediate level of SQL expertise, I am fairly new to working with XML, especially in this context. Any help/guidance would be greatly appreciated!

Answer 1

You can use merge with output to a table variable and then query the table variable to build the log XML.

Put it in a stored procedure where you have the item XML as an in parameter and the log XML as an out parameter.

create procedure AddItemXML
  @ItemsXML xml,
  @ItemsLogXML xml out
as

declare @Changes table
(
  Item_Id int,
  Name nvarchar(20),
  Price money,
  Action nvarchar(10)
);

merge Items as T
using
  (
    select T.N.value('Id[1]', 'int') as Item_Id,
           T.N.value('Name[1]', 'varchar(20)') as Name,
           T.N.value('Price[1]', 'money') as Price
    from @ItemsXML.nodes('/Item') T(N)
  ) as S
on T.Item_Id = S.Item_Id
when matched then
  update set Name = S.Name, Price = S.Price
when not matched then
  insert (Item_Id, Name, Price) values (S.Item_Id, S.Name, S.Price)
output inserted.Item_Id,
       inserted.Name,
       inserted.Price,
       $action 
  into @Changes;

set @ItemsLogXML = 
  (
    select Item_Id as ID,
           Name,
           Price
    from @Changes
    where Action = 'INSERT'
    for xml path('Item'), type
  );

Working sample on SE-Data