How to Design Database Schemas With ERD Diagrams — Free Visual Tool
Why Visual Schema Design Saves Time
Writing CREATE TABLE statements from scratch is error-prone. A visual ERD tool lets you drag-and-drop tables, define columns with types, and draw relationships — then generate the SQL automatically. You spend less time on syntax and more time thinking about your data model.
Tables, Columns, and Data Types
Start by adding tables and defining their columns. Assign data types (VARCHAR, INT, DATE, BOOLEAN, etc.) and mark primary keys. The ERD designer maps each column to the correct SQL type for your target dialect — MySQL, PostgreSQL, SQLite, or SQL Server.
Drawing Relationships
Connect tables with relationship lines to model 1:1, 1:N, and M:N associations. For M:N relationships, the tool auto-generates a junction table with foreign keys. This maps directly to SQL FOREIGN KEY constraints in the exported schema.
Exporting SQL and PNG
Once the schema is ready, export the full CREATE TABLE SQL ready to run against your database, or export the diagram as a PNG for documentation. The SQL includes primary keys, foreign key constraints, and data types based on your chosen dialect.
Who This Is Useful For
ERD diagrams are useful for developers planning new projects, teams reviewing existing schemas, and students learning database design. Having a visual representation of your schema makes it much easier to spot problems before writing any application code.
Frequently Asked Questions
Design your schema visually
Use FreeSQLKit's ERD designer to create tables, add columns, draw relationships, and export SQL — all in your browser.
Open ERD Designer