Database system software and internet databases
A DBMS is software that creates, stores, protects and retrieves data for many users; internet databases sit behind websites and apps.
Functions of a DBMS
- Data definition: create tables, fields and relationships.
- Data manipulation: add, change, delete and retrieve data, usually with SQL.
- Security: user accounts and access rights.
- Integrity: validation rules and referential integrity keep data correct.
- Concurrency control: many users at once without clashing updates.
- Backup and recovery after a failure.
- Data dictionary: stores data about the data (metadata), such as field names and types.
Database system software
| DBMS | Typical use |
|---|---|
| Microsoft Access | Desktop database for one user or a small office |
| Oracle Database | Large organisations with heavy workloads |
| Microsoft SQL Server | Business systems on Windows servers |
| MySQL | Open source; behind many websites |
| PostgreSQL | Open source; advanced features |
Talking to a database: SQL
Most relational DBMSs use SQL. For example, SELECT Name FROM Customer WHERE City = 'Kandy'; lists the names of all customers in Kandy. The same question in Access is built visually as a query.
An internet database at work
The results travel back the same way and appear as a web page. This three-part design keeps the database away from direct public access.
Examples of internet databases
- Online shop catalogues, stock and orders.
- Internet banking accounts and transactions.
- Airline and bus seat booking.
- University registration and results portals.
- Search engines and social media.
When you book a bus seat online or search for products on Daraz, your request passes through a web server to a database server, which checks availability at once. Banks keep customer accounts in large server DBMSs that serve branches, ATMs and apps together.
Short answer: “What is a DBMS? Give two examples.” Software that creates, manages and controls access to a database, e.g. Microsoft Access and Oracle.
Structured question: “Explain the functions of a database management system.” Data definition, data manipulation (SQL), security, integrity, concurrency control, backup and recovery, data dictionary.
Structured question: “What is an internet database? Explain how it works.” A database reached through a website or app. Browser → web server → database server (SQL) → results returned as a page.
A DBMS defines, manipulates, secures, shares and recovers data. Internet database = browser → web server → database server.