For creating an online DBMS, one can make use of few shared online RDBMS available on the net.
One of the sites which provide this feature is ZOHO.
(Link:http://db.zoho.com).
Once you log in to ZOHO, you will get various options for creating database for your DBMS, like Import already created database in your computer in .xls, .csv format, create database in ZOHO from various templates, entering the data right away and creating a blank database.
I have used the import database option to create my DBMS. I have used my database created in MS Excel.
You can paste the data from your file to the ZOHO window and assign a name to your database and to the tables you have imported. (You can import a database having multiple tables).
Once you have saved the tables, to retrieve any information from your database, you need to create a ‘new query table’. In this new query table window, to extract the required information in the tabular form you need to write a SQL Query in the space provided (ZOHO uses SQL platform for performing its RDBMS functions).
Save the retrieved tabular information and assign a name for it. You can repeat the process for retrieving and saving some other information.
Once you are done with this, you can decide to publish your work on the net, like I have done. You can decide to keep your database and the retrieved information a private affair, viewable only through authorization or you can keep it open for everyone using the net and is interested in viewing your database (thank you for your interest 
). For this you can use the ‘Publish’ option given on your database window.
To see my database on the summer placement scenario for Praxis Business School created using ZOHO kindly click this link:
http://db.zoho.com/ZDBDataSheetView.cc?DBID=18035000000003242&OBJID=18035000000003536
