SQL Server

Compress Text Feed to Binary

See more Compression Examples

This example receives incoming text data in chunks, compresses as a stream, and accumulates the compressed binary data. 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

    -- This example assumes the Chilkat API to have been previously unlocked.
    -- See Global Unlock Sample for sample code.

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

    DECLARE @compress int
    EXEC @hr = sp_OACreate 'Chilkat.Compression', @compress OUT

    EXEC sp_OASetProperty @compress, 'Algorithm', 'deflate'
    EXEC sp_OASetProperty @compress, 'Charset', 'utf-8'

    DECLARE @sbUncompressedChunk int
    EXEC @hr = sp_OACreate 'Chilkat.StringBuilder', @sbUncompressedChunk OUT

    EXEC sp_OASetProperty @compress, 'FirstChunk', 1
    EXEC sp_OASetProperty @compress, 'LastChunk', 0

    DECLARE @i int

    SELECT @i = 0
    WHILE @i <= 24
      BEGIN
        IF @i = 24
          BEGIN
            EXEC sp_OASetProperty @compress, 'LastChunk', 1
          END

        EXEC sp_OAMethod @sbUncompressedChunk, 'Clear', NULL
        EXEC sp_OAMethod @sbUncompressedChunk, 'AppendInt', @success OUT, @i
        EXEC sp_OAMethod @sbUncompressedChunk, 'Append', @success OUT, ': This is a line of data to be compressed...' + CHAR(13) + CHAR(10)

        EXEC sp_OAMethod @compress, 'CompressSb', @success OUT, @sbUncompressedChunk, @bdCompressed

        EXEC sp_OASetProperty @compress, 'FirstChunk', 0
        SELECT @i = @i + 1
      END

    -- Show the compressed data in hex format:

    PRINT 'The hex encoded compressed text:'
    EXEC sp_OAMethod @bdCompressed, 'GetEncoded', @sTmp0 OUT, 'hex'
    PRINT @sTmp0

    -- Now decompress in one call.  It is important to set both FirstChunk and LastChunk = 1
    DECLARE @bdDecompressed int
    EXEC @hr = sp_OACreate 'Chilkat.BinData', @bdDecompressed OUT

    EXEC sp_OASetProperty @compress, 'FirstChunk', 1
    EXEC sp_OASetProperty @compress, 'LastChunk', 1
    EXEC sp_OAMethod @compress, 'DecompressBd2', @success OUT, @bdCompressed, @bdDecompressed
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @compress, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @bdCompressed
        EXEC @hr = sp_OADestroy @compress
        EXEC @hr = sp_OADestroy @sbUncompressedChunk
        EXEC @hr = sp_OADestroy @bdDecompressed
        RETURN
      END

    DECLARE @originalText nvarchar(4000)
    EXEC sp_OAMethod @bdDecompressed, 'GetString', @originalText OUT, 'utf-8'

    PRINT @originalText

    EXEC @hr = sp_OADestroy @bdCompressed
    EXEC @hr = sp_OADestroy @compress
    EXEC @hr = sp_OADestroy @sbUncompressedChunk
    EXEC @hr = sp_OADestroy @bdDecompressed


END
GO