Object-Oriented Databases Need for Complex Data Types - CWI
Object-Oriented Databases Need for Complex Data Types - CWI
Object-Oriented Databases Need for Complex Data Types - CWI
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<strong>Data</strong>base System Concepts<br />
<strong>Data</strong>base System Concepts<br />
ODMG C++OML: <strong>Data</strong>base and <strong>Object</strong><br />
Functions<br />
Class d_<strong>Data</strong>base provides methods to<br />
open a database: open(databasename)<br />
give names to objects: set_object_name(object, name)<br />
look up objects by name: lookup_object(name)<br />
rename objects: rename_object(oldname, newname)<br />
close a database (close());<br />
Class d_<strong>Object</strong> is inherited by all persistent classes.<br />
provides methods to allocate and delete objects<br />
method mark_modified() must be called be<strong>for</strong>e an object is<br />
updated.<br />
Is automatically called when object is created<br />
8.33<br />
ODMG C++ OML: Example<br />
int create_account_owner(String name, String Address){<br />
<strong>Data</strong>base bank_db.obj;<br />
<strong>Data</strong>base * bank_db= & bank_db.obj;<br />
bank_db =>open(“Bank-DB”);<br />
d.Transaction Trans;<br />
Trans.begin();<br />
}<br />
d_Ref account = new(bank_db) Account;<br />
d_Ref cust = new(bank_db) Customer;<br />
cust->name - name;<br />
cust->address = address;<br />
cust->accounts.insert_element(account);<br />
... Code to initialize other fields<br />
Trans.commit();<br />
8.34<br />
©Silberschatz, Korth and Sudarshan<br />
©Silberschatz, Korth and Sudarshan<br />
17
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