Prisma

Prisma ORM - Type-Safe Database Toolkit

Modern database toolkit for TypeScript with schema-first development, auto-generated type-safe client, and powerful migration system.

Quick Reference

Installation

npm install prisma @prisma/client
npx prisma init

Basic Workflow

# 1. Define schema
# Edit prisma/schema.prisma

# 2. Create migration
npx prisma migrate dev --name init

# 3. Generate client
npx prisma generate

# 4. Open Studio
npx prisma studio

Core Schema Pattern

// prisma/schema.prisma
generator client {
  provider = "prisma-client-js"
}

datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")
}

model User {
  id        String   @id @default(cuid())
  email     String   @unique
  name      String?
  posts     Post[]
  createdAt DateTime @default(now())
  updatedAt DateTime @updatedAt
}

model Post {
  id        String   @id @default(cuid())
  title     String
  content   String?
  published Boolean  @default(false)
  author    User     @relation(fields: [authorId], references: [id])
  authorId  String
  createdAt DateTime @default(now())
  updatedAt DateTime @updatedAt

  @@index([authorId])
}

Type-Safe CRUD

import { PrismaClient } from '@prisma/client';

const prisma = new PrismaClient();

// Create
const user = await prisma.user.create({
  data: {
    email: 'alice@example.com',
    name: 'Alice',
    posts: {
      create: { title: 'First Post', content: 'Hello World' }
    }
  },
  include: { posts: true }
});

// Read with filters
const users = await prisma.user.findMany({
  where: { email: { contains: '@example.com' } },
  include: { posts: { where: { published: true } } },
  orderBy: { createdAt: 'desc' },
  take: 10
});

// Update
await prisma.user.update({
  where: { id: userId },
  data: { name: 'Bob' }
});

// Delete
await prisma.user.delete({ where: { id: userId } });

Schema Design Patterns

Field Types and Attributes

model Product {
  id          Int      @id @default(autoincrement())
  sku         String   @unique
  name        String
  description String?  // Optional field
  price       Decimal  @db.Decimal(10, 2)
  inStock     Boolean  @default(true)
  quantity    Int      @default(0)
  tags        String[] // Array field (PostgreSQL)
  metadata    Json?    // JSON field
  createdAt   DateTime @default(now())
  updatedAt   DateTime @updatedAt

  @@index([sku])
  @@index([name, inStock])
}

Relations

One-to-Many:

model User {
  id    String @id @default(cuid())
  posts Post[]
}

model Post {
  id       String @id @default(cuid())
  author   User   @relation(fields: [authorId], references: [id])
  authorId String

  @@index([authorId])
}

Many-to-Many:

model Post {
  id         String     @id @default(cuid())
  categories Category[] @relation("PostCategories")
}

model Category {
  id    String @id @default(cuid())
  name  String @unique
  posts Post[] @relation("PostCategories")
}

One-to-One:

model User {
  id      String   @id @default(cuid())
  profile Profile?
}

model Profile {
  id     String @id @default(cuid())
  bio    String
  user   User   @relation(fields: [userId], references: [id])
  userId String @unique
}

Self-Relations:

model User {
  id        String @id @default(cuid())
  following User[] @relation("UserFollows")
  followers User[] @relation("UserFollows")
}

Client Operations

Nested Writes

// Create with nested relations
const user = await prisma.user.create({
  data: {
    email: 'bob@example.com',
    profile: {
      create: { bio: 'Software Engineer' }
    },
    posts: {
      create: [
        { title: 'Post 1', content: 'Content 1' },
        { title: 'Post 2', content: 'Content 2' }
      ]
    }
  }
});

// Update with nested operations
await prisma.user.update({
  where: { id: userId },
  data: {
    posts: {
      create: { title: 'New Post' },
      update: {
        where: { id: postId },
        data: { published: true }
      },
      delete: { id: oldPostId }
    }
  }
});

Transactions

Sequential (Interactive):

await prisma.$transaction(async (tx) => {
  const user = await tx.user.create({
    data: { email: 'alice@example.com' }
  });

  await tx.post.create({
    data: { title: 'Post', authorId: user.id }
  });

  // Rollback if error thrown
  if (someCondition) {
    throw new Error('Rollback transaction');
  }
});

Batch (Parallel):

const [deletedPosts, updatedUser] = await prisma.$transaction([
  prisma.post.deleteMany({ where: { published: false } }),
  prisma.user.update({
    where: { id: userId },
    data: { name: 'Updated' }
  })
]);

Advanced Queries

Aggregations:

const result = await prisma.post.aggregate({
  _count: { id: true },
  _avg: { views: true },
  _sum: { likes: true },
  _max: { createdAt: true },
  where: { published: true }
});

const grouped = await prisma.post.groupBy({
  by: ['authorId'],
  _count: { id: true },
  _avg: { views: true },
  having: { views: { _avg: { gt: 100 } } }
});

Raw SQL:

// Raw query
const users = await prisma.$queryRaw<User[]>`
  SELECT * FROM "User" WHERE email LIKE ${`%${search}%`}
`;

// Execute
await prisma.$executeRaw`
  UPDATE "Post" SET views = views + 1 WHERE id = ${postId}
`;

Migrations

Development Workflow

# Create and apply migration
npx prisma migrate dev --name add_user_role

# Reset database (WARNING: deletes all data)
npx prisma migrate reset

# View migration status
npx prisma migrate status

Production Deployment

# Apply pending migrations
npx prisma migrate deploy

# Generate client (in CI/CD)
npx prisma generate

Schema Prototyping

# Push schema without migrations (dev only)
npx prisma db push

# Pull schema from existing database
npx prisma db pull

Integration Patterns

Next.js App Router

// lib/prisma.ts
import { PrismaClient } from '@prisma/client';

const globalForPrisma = globalThis as unknown as {
  prisma: PrismaClient | undefined;
};

export const prisma = globalForPrisma.prisma ?? new PrismaClient();

if (process.env.NODE_ENV !== 'production') {
  globalForPrisma.prisma = prisma;
}

Server Component:

// app/users/page.tsx
import { prisma } from '@/lib/prisma';

export default async function UsersPage() {
  const users = await prisma.user.findMany({
    include: { posts: { take: 5 } }
  });

  return (
    <ul>
      {users.map(u => (
        <li key={u.id}>{u.name} - {u.posts.length} posts</li>
      ))}
    </ul>
  );
}

Server Action:

// app/actions.ts
'use server';

import { prisma } from '@/lib/prisma';
import { revalidatePath } from 'next/cache';

export async function createPost(formData: FormData) {
  const title = formData.get('title') as string;
  const authorId = formData.get('authorId') as string;

  await prisma.post.create({
    data: { title, authorId }
  });

  revalidatePath('/posts');
}

Node.js Middleware

import { PrismaClient } from '@prisma/client';
import express from 'express';

const app = express();
const prisma = new PrismaClient();

app.get('/users/:id', async (req, res) => {
  const user = await prisma.user.findUnique({
    where: { id: req.params.id },
    include: { posts: true }
  });

  if (!user) return res.status(404).json({ error: 'Not found' });
  res.json(user);
});

app.listen(3000);

Performance Optimization

Query Optimization

// ❌ N+1 queries
const users = await prisma.user.findMany();
for (const user of users) {
  const posts = await prisma.post.findMany({
    where: { authorId: user.id }
  });
}

// ✅ Single query with include
const users = await prisma.user.findMany({
  include: { posts: true }
});

// ✅ Select specific fields
const users = await prisma.user.findMany({
  select: { id: true, email: true, posts: { select: { title: true } } }
});

Pagination

// Cursor-based (recommended for large datasets)
const posts = await prisma.post.findMany({
  take: 10,
  cursor: lastPostId ? { id: lastPostId } : undefined,
  skip: lastPostId ? 1 : 0,
  orderBy: { createdAt: 'desc' }
});

// Offset-based (simple but slower)
const posts = await prisma.post.findMany({
  skip: (page - 1) * pageSize,
  take: pageSize
});

Connection Pooling

// schema.prisma
datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")

  // Connection pool settings
  directUrl = env("DIRECT_URL")

  // Serverless connection limit
  relationMode = "prisma" // For PlanetScale, Neon
}

# .env
DATABASE_URL="postgresql://user:pass@host:5432/db?connection_limit=10&pool_timeout=20"

Prisma Studio

# Launch visual database browser
npx prisma studio

Features:

• Visual data browser and editor
• Create, read, update, delete records
• Filter and search data
• View relations visually
• Runs on localhost:5555

Prisma vs Drizzle

Choose Prisma when:

• Team prefers schema-first development
• Need visual database tools (Studio)
• Want automatic relation handling
• Building full-stack monoliths
• Rapid prototyping and migrations

Choose Drizzle when:

• Need minimal bundle size (edge functions)
• Prefer SQL-like syntax
• Edge runtime deployment (Cloudflare Workers)
• Want full control over SQL generation
• Team has strong SQL expertise

Best Practices

1. Singleton Pattern - Reuse PrismaClient instance (especially in dev)
2. Connection Management - Configure pool size for serverless
3. Select Specific Fields - Use select to reduce payload size
4. Use Transactions - For multi-step operations requiring atomicity
5. Index Strategically - Add @@index on frequently queried fields
6. Migration Discipline - Never edit migrations after deployment
7. Schema Versioning - Use descriptive migration names
8. Soft Deletes - Add deletedAt field instead of hard deletes
9. Validate Before Saving - Use Zod schemas before Prisma operations
10. Monitor Queries - Use prisma.$on('query') for logging

Common Pitfalls

❌ Creating multiple PrismaClient instances:

// WRONG - creates connection leak
function getUser() {
  const prisma = new PrismaClient(); // New instance every call
  return prisma.user.findMany();
}

// CORRECT - singleton pattern
const prisma = new PrismaClient();
function getUser() {
  return prisma.user.findMany();
}

❌ N+1 queries:

// WRONG - multiple queries
const users = await prisma.user.findMany();
for (const user of users) {
  user.posts = await prisma.post.findMany({ where: { authorId: user.id } });
}

// CORRECT - single query with include
const users = await prisma.user.findMany({ include: { posts: true } });

❌ Missing transaction for multi-step operations:

// WRONG - not atomic, can leave inconsistent state
await prisma.user.delete({ where: { id: userId } });
await prisma.post.deleteMany({ where: { authorId: userId } }); // May fail

// CORRECT - atomic transaction
await prisma.$transaction([
  prisma.post.deleteMany({ where: { authorId: userId } }),
  prisma.user.delete({ where: { id: userId } })
]);

Red Flags

Stop and reconsider if:

• Creating new PrismaClient in request handlers
• Not using transactions for multi-step operations
• Missing indexes on foreign keys or frequently queried fields
• Using findMany without pagination on large tables
• Fetching entire objects when only specific fields needed
• Not handling connection errors in production
• Using migrate dev in production (use migrate deploy)

Integration with Other Skills

• typescript-core: Zod validation, type safety patterns
• nextjs-core: Server Actions, Server Components integration
• nextjs-v16: App Router data fetching, caching
• database-migration: Safe schema evolution patterns

Resources

• Documentation: https://www.prisma.io/docs
• Schema Reference: https://www.prisma.io/docs/reference/api-reference/prisma-schema-reference
• Client API: https://www.prisma.io/docs/reference/api-reference/prisma-client-reference
• Examples: https://github.com/prisma/prisma-examples

Related Skills

When using Prisma, these skills enhance your workflow:

• drizzle: Drizzle ORM as lightweight alternative to Prisma
• typescript: TypeScript best practices for Prisma generated types
• nextjs: Prisma with Next.js: connection pooling, edge runtime considerations
• test-driven-development: Testing Prisma models, migrations, and queries

[Full documentation available in these skills if deployed in your bundle]