使用TSQL解析/查询XML

Question

I've been fighting this for a while, seems I'm close but not quite there. I have a column in a database that looks like this:

<document>
<items>
<item name="one">one is the first number</item>
<item name="two">two is the second number</item>
</items>
</document>

In this example I need to query and return 'two is the second number'. I'd also like to do this without creating a temp table. Currently I have:

create table #test (item1 xml)
insert into #test (item1) 
values ('<document> <items> <item name="one">one is the first number</item> <item name="two">two is the second number</item> </items> </document>')

select item1.value('(/document/items/item)[2]', 'nvarchar(max)') from #test
select item1.query('/document/items/item[@name="two"]') from #test

The first select returns the correct value but I need to know that it's the 2nd 'index' The second returns what I want but it returns the entire node two..

What am I missing? And, is there a simple way to use the XML without converting to a temp table?

Answer 1

I'd also like to do this without creating a temp table

You can use a variable with datatype XML.

declare @xml xml

set @xml = 
'<document>
  <items>
    <item name="one">one is the first number</item>
    <item name="two">two is the second number</item>
  </items>
</document>'

select @xml.value('(/document/items/item[@name="two"])[1]', 'nvarchar(max)')

Or you can cast your string to XML in the query.

select cast(
            '<document>
              <items>
                <item name="one">one is the first number</item>
                <item name="two">two is the second number</item>
              </items>
            </document>' as xml
           ).value('(/document/items/item[@name="two"])[1]', 'nvarchar(max)')

Your first query uses .value() which is correct and your second query has the correct XQuery expression. When using .value() you need to use a XQuery expression that returns a single value. This will give you all item nodes where @name is two /document/items/item[@name="two"]) . Adding [1] at the end makes sure that you will only get the first occurrence in the XML where @name is two.

Answer 2

(First off, rather than a temp table, you can use a variable of type xml , as I do below. Such variables can be assigned directly from string literals)

So I think you mean you want the text value of the item node with name two , in which case you just need to include the appropriate condition in the xpath you use in your value() call:

DECLARE @x xml

SET @x = '<document> <items> <item name="one">one is the first number</item> 
     <item name="two">two is the second number</item> </items> </document>'

SELECT @x.value('(/document/items/item[@name="two"])[1]', 'nvarchar(max)')

gives

--------------------------------------------------------------
two is the second number

(1 row(s) affected)