SQL Server

Compress XML Tree

See more XML Examples

Demonstrates how to compress and restore the entire subtree rooted at an XML node.

The input XML, available at http://www.chilkatsoft.com/data/compress2.xml, is this:

<root>
    <lazydog>
        <fox>The quick brown fox jumps over the lazy dog</fox>
    </lazydog>
    <fox>The quick brown fox jumps over the lazy dog</fox>
    <child>
        <grandchild>The quick brown fox jumps over the lazy dog</grandchild>
    </child>
    <child>
        <grandchild>The quick brown fox jumps over the lazy dog</grandchild>
    </child>
</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 @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

    -- The sample input XML is available at http://www.chilkatsoft.com/data/compress2.xml
    EXEC sp_OAMethod @xml, 'LoadXmlFile', @success OUT, 'compress2.xml'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @xml, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @xml
        RETURN
      END

    -- Zip compress the root node's entire subtree:
    EXEC sp_OAMethod @xml, 'ZipTree', @success OUT

    -- Examine the new XML document:
    EXEC sp_OAMethod @xml, 'GetXml', @sTmp0 OUT
    PRINT @sTmp0

    -- This is the XML w/ the compressed subtree in Base64 encoded format:

    -- <root><![CDATA[4+WyKcrPL7Hj5VIAApucxKrKlPx0KBcslJZfYReSkapQWJqZnK2QVJRfnqcAFFPIKs0tKFbIL0st
    -- UigBSoN0KgC12uiDNECN00c1jyKzkjMyc1KQHZZelJiXAhElyUwkfTBnovDoYZGNPjTUAQ==
    -- ]]></root>

    -- Now uncompress and show that the original subtree was restored:
    EXEC sp_OAMethod @xml, 'UnzipTree', @success OUT
    EXEC sp_OAMethod @xml, 'GetXml', @sTmp0 OUT
    PRINT @sTmp0

    EXEC @hr = sp_OADestroy @xml


END
GO