(SQL Server) Traverse Direct Children via FirstChild / NextSibling, or LastChild / PreviousSibling

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>

Download Chilkat XML ActiveX

CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @sTmp1 nvarchar(4000)
    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

    DECLARE @success int

    --  The sample input XML is available at http://www.chilkatsoft.com/data/fruit.xml
    EXEC sp_OAMethod @xml, 'LoadXmlFile', @success OUT, 'fruit.xml'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @xml, 'LastErrorText', @sTmp0 OUT

        PRINT @sTmp0
        RETURN
      END

    --  Iterate over the direct children by using FirstChild / NextSibling
    EXEC sp_OAMethod @xml, 'FirstChild', @child OUT
    WHILE Not (@child Is NULL )
      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

        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', NULL


    PRINT '-----'

    --  Iterate in reverse order using LastChild / PreviousSibling
    EXEC sp_OAMethod @xml, 'LastChild', @child OUT
    WHILE Not (@child Is NULL )
      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

        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', NULL

END
GO