Some fairly sophisticated classes for performing table joins
(by matching values of columns between tables) are
available in the uk.ac.starlink.table.join
package.
These work and are used in
TOPCAT,
but are not described further in this document,
and they are subject to changes in future releases.
Read the javadocs for the uk.ac.starlink.table.join
package,
or watch this space, or contact the author if you are keen to use this
functionality.