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deregister=false attribute

<< databaseName=nameofDatabase attribute | encryptionKey=key attribute >>

Derby Reference Manual

337

deregister=false attribute

Function

If set to true (the default), deregisters the embedded JDBC driver from the DriverManager
after a shutdown, so that the Derby classes can be garbage-collected.

You initially register the embedded driver by doing one of the following:

· Call the method

Class.forName("org.apache.derby.jdbc.EmbeddedDriver").newInstance(). This
mechanism works on all Java Virtual Machines (JVMs) from JDK 1.4 up.

· Set -Djdbc.drivers=org.apache.derby.jdbc.EmbeddedDriver when you boot the

Derby engine's VM, then call

DriverManager.getConnection()

. This mechanism also

works on all JVMs from JDK 1.4 up.

· Simply call DriverManager.getConnection(). This mechanism works only on JDK 6

and up.

Once the embedded driver is registered, you can shut down the Derby engine by using
the

shutdown=true

connection URL attribute. If you also specify deregister=false with the

shutdown URL, the following will happen:

· The embedded driver will remain registered.
· The Derby classes will not be garbage-collected.
· You can get a Derby connection just by issuing a call to

DriverManager.getConnection(). That is, you do not need to first call
Class.forName("org.apache.derby.jdbc.EmbeddedDriver").newInstance().

In contrast, if you use the default setting of deregister=true when you shut down the
database, the following will happen:

· The embedded driver will be deregistered.
· The Derby classes will be garbage-collected.
· You will have to call

Class.forName("org.apache.derby.jdbc.EmbeddedDriver").newInstance() before
you obtain a new Derby connection.

This attribute has no meaning if it is used with the network driver.

Combining with other attributes

This attribute is valid only when issued in conjunction with the shutdown=true attribute.

Example

-- shut down salesDB and deregister the driver
jdbc:derby:salesDB;shutdown=true
-- shut down salesDB, but do not deregister the driver
jdbc:derby:salesDB;shutdown=true;deregister=false

drop=true attribute

Function

Removes the in-memory database specified within the database connection URL.
Generates the SQLException 08006 if successful. If the database does not exist,
generates an error reporting that the database could not be found.

For a database for which authentication and SQL authorization are both enabled, only the

database owner

can drop that database.

It is not necessary to shut down the database before dropping it.