Knut Anders Hatlen points out in a comment on
DERBY-6609 that the columnAlteration syntax in the ALTER TABLE statement topic is not quite correct. It is possible to set the data type to BLOB or CLOB, in addition to VARCHAR and VARCHAR FOR BIT DATA.
Also, for VARCHAR FOR BIT DATA, he notes, "the length argument is on the wrong spot. It should be columnName SET DATA TYPE VARCHAR ( integer ) FOR BIT DATA, rather than columnName SET DATA TYPE VARCHAR FOR BIT DATA( integer )."
DERBY-6644 also requires a change to the columnAlteration syntax.