What are different issues that complicate database testing for web applications?

Web applications interface with sophisticated database management systems and build dynamic content objects created in real time using the data acquired from a database.Errors can and do occur as a consequence of each of these steps. Database testing for web applications is complicated by a variety of factors:

- Tests should be designed in such a way that they should be able to uncover errors made in translating the user's request into a form that is processed by DBMS.
- REMOTE DATABASE TO THE SERVER: Tests should be designed that uncovers errors in communication between web application and remote database.
- RAW DATA FROM DATABASE MUST BE TRANSMITTED TO WEBAPP SERVER: Tests should be designed that will demonstrate the validity of raw data received by the web application server.
- DYNAMIC CONTENT OBJECT TRANSMITTED TO CLIENT IN A FORM THAT IS DISPLAYED TO END USER: Tests should be designed to uncover errors in content object format and there should be test compatibility with client environment configurations.

Testing should ensure that :
- valid information is passed between client and server from interface layer.
- web application processes scripts correctly.
- user data is passed correctly to server.
- queries are passed to data management layer that communicates with database access routines.

User interface Layer - Tested to ensure HTML scripts are constructed properly and
transmitted to server side.
WebApp Layer on server - Ensure that user data are extracted from HTML scripts and transmitted to data transformation layer.
Data transformation function - Tested to ensure that correct SQL is created and passed to data management components.