Database Design Diagrams

Context Diagrams (Level-0 DFDs)structured analysisA Context Diagram is the highest-level Data Flow Diagram for a system. Data Flow Diagrams (DFDs)structured analysisData Flow Diagrams (DFDs) are graphical representations that model how data moves through a system. Database Schema DesignmodellingDatabase schema design is the process of translating logical data models (conceptual ERDs) into physical… Entity Relationship Diagrams (ERDs)modellingEntity Relationship Diagrams (ERDs) are visual representations of the data model in a database system. Logical Data Model (Relational Schema Diagram)modellingA Logical Data Model (LDM) — also called a Logical Schema or Relational Schema Diagram — is the intermediate… Database NormalizationmodellingNormalization is the process of organizing columns and tables in a relational database to reduce redundancy… Conceptual, Logical and Physical Data ModelsmodellingThe three levels of data modelling explained, with one online-shop example taken from conceptual entities to… Data Vault 2.0modellingData Vault 2.0 explained: hubs, links, satellites, hash keys and hash diffs, insert-only loading in SQL, and…

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

Database Design Diagrams

Diagrams in This Section (in SDLC order)

When to Use Each Diagram

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