DBMS Tutorial
Database Management Systems: data models, ER diagrams, keys, normalization, transactions and concurrency control.
A database is an organised collection of related data. A Database Management System (DBMS) is software that stores, retrieves, updates and protects that data. Examples include MySQL, PostgreSQL, Oracle and SQL Server.
DBMS vs File System
| Problem in file systems | How a DBMS solves it |
|---|---|
| Data redundancy and inconsistency | Centralised data, normalization |
| Difficult data access | Query languages (SQL) |
| Integrity problems | Constraints (keys, CHECK) |
| Atomicity problems | Transactions (ACID) |
| Concurrent-access anomalies | Concurrency control (locking) |
| Security problems | Users, roles, GRANT/REVOKE |
Database Languages
- DDL (Data Definition): CREATE, ALTER, DROP, TRUNCATE
- DML (Data Manipulation): SELECT, INSERT, UPDATE, DELETE
- DCL (Data Control): GRANT, REVOKE
- TCL (Transaction Control): COMMIT, ROLLBACK, SAVEPOINT
Database Users
Database Administrator (DBA), application programmers, sophisticated users (who write queries) and naive end users (who use forms and apps).
Track your progress through the DBMS course