SQL Server

Traverse Direct Children via FirstChild / NextSibling, or LastChild / PreviousSibling

See more XML Examples

Demonstrates some ways to iterate over direct child nodes using the FirstChild / NextSibling and LastChild / PreviousSibling methods.

The input XML, available at http://www.chilkatsoft.com/data/fruit.xml, is this:

<root>
    <fruit color="red">apple</fruit>
    <fruit color="green">pear</fruit>
    <veg color="orange">carrot</veg>
    <meat animal="cow">beef</meat>
    <xyz>
        <fruit color="blue">blueberry</fruit>
        <veg color="green">broccoli</veg>
    </xyz>
    <fruit color="purple">grape</fruit>
    <cheese color="yellow">cheddar</cheese>
</root>

SQL Server

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @sTmp1 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

    DECLARE @xml int
    EXEC @hr = sp_OACreate 'Chilkat.Xml', @xml OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    DECLARE @child int

    DECLARE @nextSibling int

    DECLARE @prevSibling int

    EXEC sp_OAMethod @xml, 'LoadXmlFile', @success OUT, 'qa_data/xml/fruit.xml'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @xml, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @xml
        RETURN
      END

    -- Iterate over the direct children by using FirstChild / NextSibling
    EXEC sp_OAMethod @xml, 'FirstChild', @child OUT
    DECLARE @bContinue int
    EXEC sp_OAGetProperty @xml, 'LastMethodSuccess', @bContinue OUT
    WHILE (@bContinue = 1)
      BEGIN
        EXEC sp_OAGetProperty @child, 'Tag', @sTmp0 OUT

        EXEC sp_OAGetProperty @child, 'Content', @sTmp1 OUT
        PRINT @sTmp0 + ' : ' + @sTmp1
        EXEC sp_OAMethod @child, 'NextSibling', @nextSibling OUT
        EXEC sp_OAGetProperty @child, 'LastMethodSuccess', @bContinue OUT
        EXEC @hr = sp_OADestroy @child

        SELECT @child = @nextSibling
      END

    PRINT '-----'

    -- Do the same, but with FirstChild2 / NextSibling2 to avoid
    -- creating so many XML object instances:
    EXEC sp_OAMethod @xml, 'FirstChild2', @success OUT
    WHILE @success = 1
      BEGIN
        EXEC sp_OAGetProperty @xml, 'Tag', @sTmp0 OUT

        EXEC sp_OAGetProperty @xml, 'Content', @sTmp1 OUT
        PRINT @sTmp0 + ' : ' + @sTmp1
        EXEC sp_OAMethod @xml, 'NextSibling2', @success OUT
      END
    -- Revert back up to the parent:
    EXEC sp_OAMethod @xml, 'GetParent2', @success OUT


    PRINT '-----'

    -- Iterate in reverse order using LastChild / PreviousSibling
    EXEC sp_OAMethod @xml, 'LastChild', @child OUT
    EXEC sp_OAGetProperty @xml, 'LastMethodSuccess', @bContinue OUT
    WHILE (@bContinue = 1)
      BEGIN
        EXEC sp_OAGetProperty @child, 'Tag', @sTmp0 OUT

        EXEC sp_OAGetProperty @child, 'Content', @sTmp1 OUT
        PRINT @sTmp0 + ' : ' + @sTmp1
        EXEC sp_OAMethod @child, 'PreviousSibling', @prevSibling OUT
        EXEC sp_OAGetProperty @child, 'LastMethodSuccess', @bContinue OUT
        EXEC @hr = sp_OADestroy @child

        SELECT @child = @prevSibling
      END

    PRINT '-----'

    -- Do the same, but with LastChild2 / PreviousSibling2 to avoid
    -- creating so many XML object instances:
    EXEC sp_OAMethod @xml, 'LastChild2', @success OUT
    WHILE @success = 1
      BEGIN
        EXEC sp_OAGetProperty @xml, 'Tag', @sTmp0 OUT

        EXEC sp_OAGetProperty @xml, 'Content', @sTmp1 OUT
        PRINT @sTmp0 + ' : ' + @sTmp1
        EXEC sp_OAMethod @xml, 'PreviousSibling2', @success OUT
      END
    -- Revert back up to the parent:
    EXEC sp_OAMethod @xml, 'GetParent2', @success OUT

    EXEC @hr = sp_OADestroy @xml


END
GO