Database Design Diagrams

Database design diagrams are visual tools used during the analysis and design phases of the Software Development Life Cycle (SDLC) to model data structure, flow, and relationships. These diagrams help teams communicate data architecture, document integration points, and validate designs before implementation.

Diagrams in This Section (in SDLC order)

• Context Diagrams — The highest-level view: the entire system as a single process surrounded by external entities. First diagram produced in structured analysis; defines system scope and boundary.
• Data Flow Diagrams (DFD) — Decomposition of the context diagram. Model how data moves through a system: processes, data stores, external entities, and flows across level-0, level-1, and deeper levels.
• Entity-Relationship Diagrams (ERD) — Model entities, attributes, and relationships. Foundation for conceptual and logical database design with cardinality notation.
• Logical Data Model — The bridge between ERD and physical schema. Tables, columns, PKs, FKs, and constraints in a DBMS-independent form.
• Normalization — 1NF / 2NF / 3NF / BCNF / 4NF / 5NF plus denormalization trade-offs. Uses functional dependencies to eliminate redundancy and prevent update anomalies.
• Database Schema Design — Physical design, star/snowflake schemas, indexing, partitioning, constraints, and performance optimization.

When to Use Each Diagram

• Requirements & scoping: Context Diagrams
• System integration analysis: Data Flow Diagrams
• Conceptual data modeling: Entity-Relationship Diagrams
• Bridging ERD to physical tables: Logical Data Model
• Reducing redundancy & anomalies: Normalization
• Physical implementation & performance tuning: Database Schema Design