Who are the Database Users?

Database Users
- Users are differentiated by the way they expect to interact with the system
- Application programmers – interact with system through DML calls
- Sophisticated users – form requests in a database query language
- Specialized users – write specialized database applications that do not fit into the traditional data processing framework
- Naïve users – invoke one of the permanent application programs that have been written previously
E.g. people accessing database over the web, bank tellers, clerical staff

Database Administrator
- Coordinates all the activities of the database system; the database administrator has a good understanding of the enterprise’s information resources and needs.
- Database administrator's duties include:
• Schema definition
• Storage structure and access method definition
• Schema and physical organization modification
• Granting user authority to access the database
• Specifying integrity constraints
• Acting as liaison with users
• Monitoring performance and responding to changes in requirements

Transaction Management
- A transaction is a collection of operations that performs a single logical function in a database application
- Transaction-management component ensures that the database remains in a consistent (correct) state despite system failures (e.g., power failures and operating system crashes) and
transaction failures.
- Concurrency-control manager controls the interaction among the concurrent transactions, to ensure the consistency of the database.

Storage Management
- Storage manager is a program module that provides the interface between the low-level data stored in the database and the application programs and queries submitted to the system.
- The storage manager is responsible to the following tasks:
• interaction with the file manager
• efficient storing, retrieving and updating of data

Overall System Structure



Application Architectures
Two-tier architecture: E.g. client programs using ODBC/JDBC to communicate with a database
Three-tier architecture: E.g. web-based applications, and applications built using “middleware”