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3 templates · ERD

Database Schema ER Diagram Examples

A database schema ER diagram is the definitive blueprint for understanding a relational database — every table, every column, every relationship laid out with precision.

Standard Chen 1976 / Everest 1976 (crow's foot)Engine schematex-erdExport SVG · PNG · PDF
3 templates
ERD Database Schema ER
Multi-tenant SaaS RBAC schema — ER DiagramMulti-tenant SaaS RBAC schema — ER DiagramDatabase Schema ERUse template →E-commerce schema — ER DiagramE-commerce schema — ER DiagramDatabase Schema ERUse template →University schema (academic ERD) — ER DiagramUniversity schema (academic ERD) — ER DiagramDatabase Schema ERUse template →

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How to

How to use an erd template.

  1. 01List your entities (tables)

    Name each table in your database — for example, User, Product, Order, Payment. Each entity becomes a box in the ER diagram.

  2. 02Define attributes for each entity

    For each table, list the key attributes: primary key, required fields, and any important optional fields. Include data types if you want them shown.

  3. 03Describe relationships between entities

    Explain how entities relate — 'A User can place many Orders,' 'Each Order has one or more Products.' The AI determines the correct cardinality (1:1, 1:N, M:N).

  4. 04Specify foreign keys and junction tables

    For many-to-many relationships, describe the junction table — for example, 'OrderItems links Orders and Products with quantity and price.' The AI will represent it correctly.

  5. 05Export for documentation

    Download the ER diagram as PNG or SVG for your technical specification, README, or database documentation.

FAQ

Questions about erd templates

What is an ER diagram?

An ER (entity-relationship) diagram is a visual representation of a database schema. It shows tables (entities), their attributes (columns), and the relationships between them, including cardinality and key constraints.

What is the difference between a conceptual, logical, and physical ER diagram?

A conceptual ER diagram shows entities and relationships without implementation details. A logical ER diagram adds attributes, primary keys, and foreign keys. A physical ER diagram includes data types, indexes, and database-specific constraints.

How do I represent a many-to-many relationship in an ER diagram?

Use a junction (associative) table that contains foreign keys to both related entities plus any additional attributes of the relationship. For example, an OrderItems table between Orders and Products.

What notation does ChatDiagram use for ER diagrams?

ChatDiagram uses crow's foot notation by default — the most widely used ER notation in industry and academia. It clearly shows one, many, zero-or-one, and zero-or-many cardinalities.

Can I generate an ER diagram from an existing SQL schema?

Yes. Paste your CREATE TABLE statements into ChatDiagram and ask it to generate an ER diagram. The AI parses the SQL and produces a visual representation of your existing schema.