Welcome to the Ranch!
First of all, how does the code fail in MySQL? Just saying "it does not work"
is not very useful.
I don't use MySQL myself, but what I've found by googling
mysql append to blob seems to suggest you need to use the
CONCAT function in MySQL to add to a BLOB.
Also,
this page says:
The BLOB implementation does not allow in-place modification (they are copies, as reported by the DatabaseMetaData.locatorsUpdateCopies() method). Because of this, use the corresponding PreparedStatement.setBlob() or ResultSet.updateBlob() (in the case of updatable result sets) methods to save changes back to the database.
I'm afraid that might mean that appending to an existing blob is not supported by Connector/J.