To date, most applications based on the framework have used mysql, though postgres has also been
used successfully.   With mysql you can initialize a new database by running the
commands in sdk/scripts/database/cipres.sql.  Another way to initialize a new database,
that should work with any database server, is to build the framework and then 
run sdk/scripts/sdkrun org.ngbw.utils.CreateTables to automatically initialize the database. The
utility has one optional argument, --drop, which instructs it to execute drop statements before
creating database objects. A third way would be to run sdk/scripts/database/create_cipres_sql.sh
to generate the necessary SQL commands, and then execute those manually. The script also
recognizes an optional --drop argument, which instructs it to generate drop statements.

How do you configure the sdk to use a particular database server?
You need to set the correct value for the database.url property in build.properties, and set the 
value of database.driverClass to the class name of the JDBC driver for the database server. After 
that CreateTables will be able to query the database server for metadata, so that it can produce 
the correct commands to initialize the database.  The specified driver is used for all
the framework's database access, however there are a few python scripts in sdk/scripts, that
are typically run from cron, that may only work with mysql.