Entity relationship diagram (ERD) maker
Click + Table, type the name and the fields and drag it into place. Connect the tables and pick the cardinality.
How to useThe whole database in one drawing
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Entity relationship diagram (ERD) maker: what it is for
Type the entities with their columns and types, mark the primary, foreign and unique keys and connect the entities with their cardinality (one, zero or one, one or more, zero or more). The diagram appears in crow's foot notation.
If your database already exists, the SQL to ER diagram tool builds the drawing from the CREATE TABLE statements.
How to use
- Type the entities and columns.
- Connect the entities with the cardinality.
- Download the ERD as PNG or SVG.
When to use it
- Designing a system database.
- Database coursework.
- Documenting the tables of a project.
Frequently asked questions
How do I write the cardinality?
The symbols on each side of the link say how many: || is exactly one, |o is zero or one, }| is one or more and }o is zero or more. CUSTOMER ||--o{ ORDER means a customer has zero or more orders and each order has one customer.
How do I mark primary and foreign keys?
After the column name write PK (primary key), FK (foreign key) or UK (unique). A column can have more than one, separated by a comma: int order_id PK, FK.
I already have the SQL. Do I need to type everything again?
No. Use the SQL to ER diagram tool: paste the CREATE TABLE statements and it builds the diagram with the keys and links.
Is it really free?
Yes, 100% free. No sign-up, no subscription and no usage limits. All Tools123 tools are free and run right in your browser.