How to update Next.js prima app after doing database changes in prisma.schema

After updating your schema.prisma file, you need to apply the changes to your PostgreSQL database. Follow these steps to properly update your schema:

Step 1: Check Changes in `schema.prisma`

Modify your schema.prisma file with new fields, models, or relationships.

Example:
If you initially had:

model User {
  id    String  @id @default(uuid())
  name  String
  email String  @unique
  createdAt DateTime @default(now())
}

And you add a new field age:

model User {
  id    String  @id @default(uuid())
  name  String
  email String  @unique
  age   Int?   // New optional field
  createdAt DateTime @default(now())
}

Step 2: Create a New Migration

After updating schema.prisma, create a new migration:

npx prisma migrate dev --name add-age-field

✅ This will:

Generate a SQL migration file inside prisma/migrations/.
Apply the migration to your PostgreSQL database.

Step 3: Regenerate Prisma Client

Whenever you make schema changes, regenerate the Prisma Client:

npx prisma generate

This ensures your application uses the latest schema.

Step 4: Check If Changes Applied

Run Prisma Studio to inspect your database:

npx prisma studio

Or check directly with SQL:

psql -d mydatabase -U myuser -c '\d+ "User"'

Step 5: Deploy Changes in Production

If running in production, apply migrations with:

npx prisma migrate deploy

🚀 This ensures the database schema is updated without affecting existing data.

Step 6: Handle Data Migration (If Needed)

If you removed or changed a column, you may need to migrate the data manually:

Use SQL:

UPDATE "User" SET age = 25 WHERE age IS NULL;

Or write a Prisma script:

import { PrismaClient } from '@prisma/client';
const prisma = new PrismaClient();

async function updateUsers() {
  await prisma.user.updateMany({
    data: { age: 25 }, 
    where: { age: null }
  });
  console.log("Updated users!");
}

updateUsers().finally(() => prisma.$disconnect());

Quick Summary

Action	Command
Edit `schema.prisma`	Modify models & fields
Create new migration	`npx prisma migrate dev --name <migration-name>`
Regenerate Prisma Client	`npx prisma generate`
View database	`npx prisma studio`
Apply changes in production	`npx prisma migrate deploy`
Handle data migration	Use SQL or Prisma script

✅ Now your database schema is updated and ready to use! Let me know if you need further guidance. 🚀

Step 1: Check Changes in schema.prisma