usage_database_create_drop.txt

LiteSQL is a C++ library that integrates C++ objects tightly to relational database and thus provide

/*sLiteSQL - Documentathon
 * 
 * By Tero Laitinen 
 * 
 * See LICENSE for copyright information. */
/* \file documentation.txt
    Manual */

/** \page usage_database_create_drop Creating and Dropping Database

The code below defines a simple database:
\code
<?xml version="1.0"?>
<!DOCTYPE database SYSTEM "litesql.dtd">
<database name="PersonDatabase">
    <object name="Person">
        <field name="name" type="string"/>
    </object>
</database>
\endcode

The database file is created when PersonDatabase is constructed. First argument
of constructor is requested backend. Other possibilities are "postgresql"
and "mysql". Refer to class documentation for details.
\code
PersonDatabase db("sqlite3", "database=person.db");
\endcode

The database has to be created before any Persistent - classes can be used.
\code
db.create();
\endcode

The database can be dropped using drop() - method.
\code
db.drop();
\endcode

Suppose the database schema has changed along with new features of the program.
Few data fields has been added to Person-class and completely new 
Persistent-class House has been defined. To upgrade database on disk, use
needsUpgrade() and upgrade() - methods.
\code
if (db.needsUpgrade())
    db.upgrade();
\endcode

If new fields has been added to classes, the upgrade operation may be quite 
costly. All backends do not support table modifications so records has 
to be copied forth and back. 

Upgrade routine will try to preserve data. It will drop fields that are not
in new schema and insert NULL-values to new fields.

*/