(SQL Server) Compress Text Feed to Binary

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

The purpose is to demonstrate the BeginCompressString, MoreCompressString, and EndCompressString methods.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

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

    DECLARE @success int

    DECLARE @compressedData int
    -- Use "Chilkat_9_5_0.BinData" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.BinData', @compressedData OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    DECLARE @compress int
    -- Use "Chilkat_9_5_0.Compression" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.Compression', @compress OUT

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

    DECLARE @sbIndex int
    -- Use "Chilkat_9_5_0.StringBuilder" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.StringBuilder', @sbIndex OUT

    DECLARE @i int

    SELECT @i = 0
    WHILE @i <= 24
      BEGIN
        -- Note: It is possible (and normal) for a BeginCompress* or MoreCompress* method to return
        -- an empty string (or 0 bytes).  When this happens, the input data is not lost.  It will be flushed
        -- in a subsequent call.
        EXEC sp_OAMethod @sbIndex, 'Clear', NULL
        EXEC sp_OAMethod @sbIndex, 'AppendInt', @success OUT, @i
        IF @i = 0
          BEGIN
            EXEC sp_OAMethod @sbIndex, 'GetAsString', @sTmp0 OUT
            EXEC sp_OAMethod @compress, 'BeginCompressString', @compressedBytes OUT, @sTmp0
          END
        ELSE
          BEGIN
            EXEC sp_OAMethod @sbIndex, 'GetAsString', @sTmp0 OUT
            EXEC sp_OAMethod @compress, 'MoreCompressString', @compressedBytes OUT, @sTmp0
          END
        EXEC sp_OAMethod @compressedData, 'AppendBinary', @success OUT, @compressedBytes
        EXEC sp_OAMethod @compress, 'MoreCompressString', @compressedBytes OUT, ': This is a line of data to be compressed...' + CHAR(13) + CHAR(10)
        EXEC sp_OAMethod @compressedData, 'AppendBinary', @success OUT, @compressedBytes
        SELECT @i = @i + 1
      END

    -- Flush any remaining output.
    EXEC sp_OAMethod @compress, 'EndCompressString', @compressedBytes OUT
    EXEC sp_OAMethod @compressedData, 'AppendBinary', @success OUT, @compressedBytes

    -- Show the compressed data in hex format:

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

    -- Now decompress in one call:
    EXEC sp_OAMethod @compressedData, 'GetBinary', @compressedBytes OUT
    DECLARE @originalText nvarchar(4000)
    EXEC sp_OAMethod @compress, 'DecompressString', @originalText OUT, @compressedBytes

    PRINT @originalText

    EXEC @hr = sp_OADestroy @compressedData
    EXEC @hr = sp_OADestroy @compress
    EXEC @hr = sp_OADestroy @sbIndex


END
GO