Generate ER diagram

Render tables, keys, and foreign-key relationships as an entity-relationship diagram.

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ToolER Diagram Generator
Input
Output
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How it works

Tables become entities with typed columns, primary keys, and foreign-key edges; cardinality determines one-to-one, one-to-many, or many-to-many connectors. Relationships are rendered from declared schema text rather than guessed from names.

  • Keys provide portable evidence for edges.
  • Undeclared same-name columns remain independent.

Worked example

Blog Schema
Generate an ER diagram from users and posts tables
Input
											CREATE TABLE users (
  id INTEGER PRIMARY KEY,
  name VARCHAR(100) NOT NULL
);

CREATE TABLE posts (
  id INTEGER PRIMARY KEY,
  title VARCHAR(255),
  user_id INTEGER REFERENCES users(id)
);
Output
												erDiagram
    users {
        INTEGER id "PK"
        VARCHAR(100) name
    }
    posts {
        INTEGER id "PK"
        VARCHAR(255) title
        INTEGER user_id "FK"
    }
    users ||--o{ posts : "user_id"

When to use this

Schema reviews, migration planning, and data-team documentation render ER diagrams.

Edge cases

  • Nullable foreign keys represent optional relationships.
  • Many-to-many data needs a join table.
  • A same-named column without a constraint is only a convention.

References