Prisma Schema Visualizer

Prisma Schema is a declarative data modeling language used by Prisma ORM. You define models (database tables), their fields (columns), relations (foreign keys), and constraints in a schema.prisma file. Prisma generates a type-safe database client from this schema, handles migrations, and provides an introspection tool to generate the schema from an existing database.

One-to-many: add a list field (posts Post[]) on the parent model and a scalar foreign key plus @relation on the child. One-to-one: same but without [] and with @unique on the foreign key. Many-to-many: add list fields on both models — Prisma creates the junction table automatically. For explicit many-to-many with extra fields, create a join model manually.

@id marks the field as the primary key. @default(autoincrement()) makes the database auto-assign incrementing integers. Alternatives: @default(cuid()) for short unique strings, @default(uuid()) for standard UUIDs, @default(nanoid()) for URL-safe IDs, or @default(dbgenerated()) to use database-specific functions.

In Prisma, String maps to VARCHAR/TEXT. String? (with ?) makes the field optional (nullable) — the column allows NULL. String (without ?) makes it required — NOT NULL. String[] is only available for databases that support arrays (PostgreSQL). Always use ? for fields you know can be empty, like optional bio, phone, or address fields.

Run npx prisma migrate dev --name add_user_model during development — this creates a migration SQL file and applies it to your dev database. Run npx prisma migrate deploy in production/CI — this applies pending migrations without creating new ones. Run npx prisma db push for rapid prototyping without migration history (useful in early development).

Run npx prisma generate after any schema change. The Prisma client is auto-generated TypeScript code tailored to your schema — it provides prisma.user.findMany(), prisma.post.create(), etc. with full type safety. Add this to your postinstall script in package.json so the client is regenerated when teammates pull new changes.