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2008-03-10

Using SQL Server 2005 XML And Unpivot

I have a table with contracts stored as XML. Using the XML query possibilities in SQL Server 2005 together with the UNPIVOT keyword I can get statistics on different types of contracts.

My table has these columns:
ContractNumber int (Primary Key)
contractXML xml

My XML looks something like like this, and is stored in a column of type XML:

<Contract>
  <Customer>
  ...
  </Customer>

  <Order>
    <OrderItem>
      <Name>Product1</Name>
      <Price>123.00</Price>
    </OrderItem>
    <OrderItem>
      <Name>Product1</Name>
      <Price>123.00</Price>
    </OrderItem>
    <OrderItem>
      <Name>Product3</Name>
      <Price>13.00</Price>
    </OrderItem>
    <OrderItem>
      <Name>Product2</Name>
      <Price>23.00</Price>
    </OrderItem>
    <OrderItem>
      <Name>Product1</Name>
      <Price>123.00</Price>
    </OrderItem>
  </Order>
</Contract>

To get a table with a max of 5 OrderItems as columns, I can use this query:

    SELECT
      ContractNumber,
      contractXML.value('(/Contract/Order/OrderItem/Name)[1]','varchar(50)') AS Product1,
      contractXML.value('(/Contract/Order/OrderItem/Name)[2]','varchar(50)') AS Product2,
      contractXML.value('(/Contract/Order/OrderItem/Name)[3]','varchar(50)') AS Product3,
      contractXML.value('(/Contract/Order/OrderItem/Name)[4]','varchar(50)') AS Product4,
      contractXML.value('(/Contract/Order/OrderItem/Name)[5]','varchar(50)') AS Product5
    FROM Contract

 

This is nice, but what if I want to get the number of each product sold? The answer is that I can use the UNPIVOT operator!
Something like this will do it:

SELECT Name, COUNT(*) AS [Count] FROM
(
    SELECT
        ContractNumber, col, Name
    FROM
    (SELECT
    ContractNumber,
    [col1] = contractXML.value('(/Contract/Order/OrderItem/Name)[1]','varchar(50)'),
    [col2] = contractXML.value('(/Contract/Order/OrderItem/Name)[2]','varchar(50)'),
    [col3] = contractXML.value('(/Contract/Order/OrderItem/Name)[3]','varchar(50)'),
    [col4] = contractXML.value('(/Contract/Order/OrderItem/Name)[4]','varchar(50)'),
    [col5] = contractXML.value('(/Contract/Order/OrderItem/Name)[5]','varchar(50)')
    FROM Contract) col
    UNPIVOT(
        Name
        FOR col
        IN ([col1],[col2],[col3],[col4],[col5])
    ) AS unpvt
) AS T
GROUP BY PackageName

The UNPIVOT operator gives the values in the 5 columns as 1 column.

If I had only the 1 row in my Contract table from the example above, the result would be:

Name Count
Product1 3
Product2 1
Product3 1

This is a simple example, and it has a max number of ordered products per contract of 5. Could maybe be extended.

If you want a table with the counts for the different products as columns, then something like this would do the job:

SELECT
   SUM(contractXML.value('count(/Contract/Order/OrderItem[Name="Product1"])','int')) AS Product1,
   SUM(contractXML.value('count(/Contract/Order/OrderItem[Name="Product2"])','int')) AS Product2,
   SUM(contractXML.value('count(/Contract/Order/OrderItem[Name="Product3"])','int')) AS Product3
FROM Contract

This would give this result:

Product1 Product2 Product3
3 1 1

And we could of course UNPIVOT this result too:

SELECT
   ProcuctCount
FROM
(SELECT
   SUM(contractXML.value('count(/Contract/Order/OrderItem[Name="Product1"])','int')) AS Product1,
   SUM(contractXML.value('count(/Contract/Order/OrderItem[Name="Product2"])','int')) AS Product2,
   SUM(contractXML.value('count(/Contract/Order/OrderItem[Name="Product3"])','int')) AS Product3
FROM Contract) cols
UNPIVOT(
   ProductCount
   FOR cols IN (Product1, Product2, Product3)
) AS unpvt

This should give a table like this:

ProductCount
3
1
1

2008-03-03

Apache Leap Year Bug

Seems Apache (Web Server) has some rather embarrassing problems with leap years: http://blogs.lodgon.com/johan/Leap_year_issues_in_apache_commonsnet
https://issues.apache.org/jira/browse/NET-188