Learning Objectives
- Define a database and a DBMS.
- State problems of traditional file-based systems.
- Identify the components and users of a database system.
- List the advantages and limitations of the database approach.
- Preview models and business intelligence.
Next: data concepts, database vs file system, models, DBMS, BI.
Database
A database is an organized collection of related data stored so that many users and programs can retrieve it consistently. Examples: a student information system, an inventory file, a bank’s account records.
A Database Management System (DBMS) is the software that creates, stores, updates, and retrieves that data on behalf of users and applications. Examples: Microsoft Access, MySQL, PostgreSQL, Oracle, Microsoft SQL Server.
Exam tip: a database is the data; a DBMS is the software. Together with users and procedures they form a database system.
File systems versus the database approach
Spreadsheets and folders work for one person. They produce redundancy (the same customer stored twice), inconsistency (two different phone numbers), weak security, and no standard query language. A DBMS (Access, MySQL, Oracle) sits between users and the data: it defines structure, enforces keys, controls access, and supports backup.
flowchart LR
U[Users and Apps] --> DBMS[DBMS]
DBMS --> DB[(Central Database)]
FS[Separate Files] -.->|Redundancy Inconsistency| P[Problems at Scale]
Figure 1: DBMS as Central Data Manager
Worked example: one student, three files
| Office | File | Student phone |
|---|---|---|
| Admissions | admission.xls | 9841-000111 |
| Accounts | fees.xls | 9841-000111 |
| Exam section | marks.xls | 9851-000222 |
The student changed numbers, but only the exam section updated its file. The college now has redundant data (the phone is stored three times) and inconsistent data (two different numbers). In a database, the phone number is stored once in a Students table and every office reads the same record.
Components of a database system
- Data — the stored facts, organized into tables, records, and fields.
- Hardware — servers, storage disks, and the network that connects users.
- Software — the DBMS plus the applications (forms, apps, websites) built on it.
- Users — the people who interact with the data (see below).
- Procedures — rules for using, backing up, and securing the database.
Who uses a database?
- End users — clerks, customers, and managers who enter and view data through forms and reports.
- Application developers — write the programs that read and update the database.
- Database Administrator (DBA) — designs the structure, grants access, monitors performance, and runs backups.
Advantages and limitations of the database approach
| Advantages | Limitations |
|---|---|
| Less redundancy and better consistency | DBMS licences, servers, and skilled staff cost more |
| Data shared by many users and departments | More complex to design and maintain |
| Central security and access control | A failure can stop many departments at once |
| Standard query language (SQL) for reports | Needs regular backup and recovery planning |
| Integrity rules (e.g. no duplicate StudentID) | Small, one-person tasks may not justify it |
Why managers care
Better data quality supports decisions, customer service, and compliance. Business intelligence later in this unit is the practice of analyzing that stored data for trends—not replacing operational databases, but using them.
Nepal / lab example
A college that keeps marks only in each teacher’s Excel file cannot produce a reliable transcript. One database with StudentID as a key (see Lab 6) is the database approach.
Similarly, a bank’s core banking system lets a customer deposit cash in Butwal and withdraw it in Kathmandu minutes later, because every branch reads and updates the same account database.
Key Takeaways
- A database is related data; a DBMS is the software that manages it.
- File systems do not scale well for shared, accurate records: they cause redundancy and inconsistency.
- A database system has five components: data, hardware, software, users, and procedures.
- The database approach costs more but gives consistency, sharing, security, and better reporting.
- BI depends on having trustworthy operational data.
Discussion Questions
- Give one redundancy example from a paper-based office.
- Who should be allowed to delete a student record, and why?
- Is Excel ever acceptable as a “database”? When does it stop being enough?
Exam-Style Questions
Short answer
- Define database and DBMS with one example each.
- What is data redundancy? How does it lead to inconsistency?
- List the five components of a database system.
Long answer
- “The database approach overcomes the limitations of the traditional file system.” Discuss with a suitable business example.
- Explain the roles of end users, application developers, and the database administrator in an organization.
