Re: Uniquely identifying a record in SQL without a unique key?

Mark S Waterbury wrote:

See:
http://www.tutorialspoint.com/jdbc/index.htm

See especially the link "JDBC - Result Sets" on the left.

Their so-called "award-winning tutorial" (what kind of award? The DARWIN Award?) starts out fine, but turns to bupkis when it gets to updating the database:

As soon as their own example code,
http://www.tutorialspoint.com/jdbc/updating-result-sets.htm
gets to

rs.updateDouble( "age", newAge );

it throws

com.mysql.jdbc.NotUpdatable: Result Set not updatable (referenced table has no primary keys).This result set must come from a statement that was created with a result set type of ResultSet.CONCUR_UPDATABLE, the query must select only one table, can not use functions and must select all primary keys from that table. See the JDBC 2.1 API Specification, section 5.6 for more details.
at com.mysql.jdbc.UpdatableResultSet.generateStatements(UpdatableResultSet.java:621)
at com.mysql.jdbc.UpdatableResultSet.syncUpdate(UpdatableResultSet.java:1530)
at com.mysql.jdbc.UpdatableResultSet.updateDouble(UpdatableResultSet.java:2056)
at com.mysql.jdbc.UpdatableResultSet.updateDouble(UpdatableResultSet.java:2084)

They provide no direct link to email the author, just a very-low-traffic BBS, and when I signed up and posted my complaint thereon, I got back a message accusing me of spamming the board.

Anybody know of tutorials that actually work, by non-anonymous authors?

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JHHL