(SQL Server) Transition from BeginCompressStringENC to FirstChunk/LastChunk

Provides instructions for replacing deprecated BeginCompressStringENC method calls with using FirstChunk/LastChunk properties.

Note: This example requires Chilkat v11.0.0 or greater.

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)
    DECLARE @sTmp1 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 @sbCompressedBase64 int
    EXEC @hr = sp_OACreate 'Chilkat.StringBuilder', @sbCompressedBase64 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'
    EXEC sp_OASetProperty @compress, 'EncodingMode', 'base64'

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

    -- ----------------------------------------------------------------------------------
    -- This is the deprecated way of compressing in chunks using Begin/More/End methods..
    -- ----------------------------------------------------------------------------------
    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', @sTmp1 OUT
            EXEC sp_OAMethod @compress, 'BeginCompressStringENC', @sTmp0 OUT, @sTmp1
            EXEC sp_OAMethod @sbCompressedBase64, 'Append', @success OUT, @sTmp0
          END
        ELSE
          BEGIN
            EXEC sp_OAMethod @sbIndex, 'GetAsString', @sTmp1 OUT
            EXEC sp_OAMethod @compress, 'MoreCompressStringENC', @sTmp0 OUT, @sTmp1
            EXEC sp_OAMethod @sbCompressedBase64, 'Append', @success OUT, @sTmp0
          END
        EXEC sp_OAMethod @compress, 'MoreCompressStringENC', @sTmp0 OUT, ': This is a line of data to be compressed...' + CHAR(13) + CHAR(10)
        EXEC sp_OAMethod @sbCompressedBase64, 'Append', @success OUT, @sTmp0
        SELECT @i = @i + 1
      END

    -- Flush any remaining output.
    EXEC sp_OAMethod @compress, 'EndCompressStringENC', @sTmp0 OUT
    EXEC sp_OAMethod @sbCompressedBase64, 'Append', @success OUT, @sTmp0


    PRINT 'The base64 encoded compressed text:'
    EXEC sp_OAMethod @sbCompressedBase64, 'GetAsString', @sTmp0 OUT
    PRINT @sTmp0

    -- Decompress in one call:
    DECLARE @originalText nvarchar(4000)
    EXEC sp_OAMethod @sbCompressedBase64, 'GetAsString', @sTmp0 OUT
    EXEC sp_OAMethod @compress, 'DecompressStringENC', @originalText OUT, @sTmp0

    PRINT @originalText

    -- ----------------------------------------------------------------------------------
    -- This is new way of compressing in chunks using FirstChunk and LastChunk properties
    -- ----------------------------------------------------------------------------------

    EXEC sp_OAMethod @sbCompressedBase64, 'Clear', NULL

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

    DECLARE @bdCompressed int
    EXEC @hr = sp_OACreate 'Chilkat.BinData', @bdCompressed OUT

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

    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


    PRINT 'The base64 encoded compressed text:'
    EXEC sp_OAMethod @bdCompressed, 'GetEncoded', @sTmp0 OUT, 'base64'
    PRINT @sTmp0

    -- Decompress in one call:
    EXEC sp_OAMethod @bdCompressed, 'GetEncoded', @sTmp0 OUT, 'base64'
    EXEC sp_OAMethod @compress, 'DecompressStringENC', @originalText OUT, @sTmp0

    PRINT @originalText

    EXEC @hr = sp_OADestroy @sbCompressedBase64
    EXEC @hr = sp_OADestroy @compress
    EXEC @hr = sp_OADestroy @sbIndex
    EXEC @hr = sp_OADestroy @bdCompressed
    EXEC @hr = sp_OADestroy @sbUncompressedChunk


END
GO