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Database Schema Diagram: From Tables to Reviewable ERD

Turn schema text into a diagram people can actually review.

5 min read · Free, no sign-up · Updated 2026-09-05

A database schema diagram is the quickest way to review table structure without reading a wall of DDL. The diagram should show tables, columns, primary keys, foreign keys and the relationships between them, but it should also be editable because schema reviews almost always lead to changes.

FlowDiagram can start from SQL. Paste CREATE TABLE statements and it creates entity tables with typed columns and relationship connectors. You can then move tables, trim noisy columns, add comments and export the result.

What makes a schema diagram readable

• Table names are grouped by domain. Customer, billing and fulfillment tables should not be scattered randomly.
• Relationship lines attach to the relevant rows. Readers should see which foreign key column points where.
• Noisy audit columns are hidden or reduced. Created and updated timestamps matter in the schema, but not in every review diagram.
• Important comments are visible. A table comment can explain intent faster than a dense column list.

Use it both directions

The same diagram can become SQL again. That makes FlowDiagram useful for quick design sessions: sketch the entities, discuss relationships, then export DDL or DBML for the next step.

Frequently asked questions

Can I create a schema diagram from SQL?

Yes. Paste CREATE TABLE statements and FlowDiagram creates editable entity tables and relationship lines.

Does it support crow-foot relationships?

Yes. Foreign keys are drawn as crow-foot relationship connectors, including one-to-many notation.

Can I export the schema again?

Yes. You can export DDL, DBML, Mermaid, a data dictionary, PNG, SVG or PDF.