prisma-database-setup-mysql

MySQL Setup

Configure Prisma with MySQL (or MariaDB).

Prerequisites

• MySQL or MariaDB database
• Connection string

1. Schema Configuration

In prisma/schema.prisma:

datasource db {
  provider = "mysql"
}

generator client {
  provider = "prisma-client"
  output   = "../generated"
}

2. Config Configuration (v7)

In prisma.config.ts:

import { defineConfig, env } from 'prisma/config'

export default defineConfig({
  schema: 'prisma/schema.prisma',
  datasource: {
    url: env('DATABASE_URL'),
  },
})

3. Environment Variable

In .env:

DATABASE_URL="mysql://user:password@localhost:3306/mydb"

Connection String Format

mysql://USER:PASSWORD@HOST:PORT/DATABASE

• USER: Database user
• PASSWORD: Password
• HOST: Hostname
• PORT: Port (default 3306)
• DATABASE: Database name

Driver Adapter (Prisma ORM 7 required)

Prisma ORM 7 uses the query compiler by default, so you must use a driver adapter.

1. Install adapter and driver:

   npm install @prisma/adapter-mariadb mariadb
   

2. Instantiate Prisma Client with the adapter:

   import 'dotenv/config'
   import { PrismaClient } from '../generated/client'
   import { PrismaMariaDb } from '@prisma/adapter-mariadb'
   
   const adapter = new PrismaMariaDb({
     host: 'localhost',
     port: 3306,
     connectionLimit: 5,
     user: process.env.MYSQL_USER,
     password: process.env.MYSQL_PASSWORD,
     database: process.env.MYSQL_DATABASE,
   })
   
   const prisma = new PrismaClient({ adapter })
   

PlanetScale Setup

PlanetScale uses MySQL but requires specific settings because it doesn't support foreign key constraints.

In prisma/schema.prisma:

datasource db {
  provider     = "mysql"
  relationMode = "prisma" // Emulate foreign keys in Prisma
}

Common Issues

"Too many connections"

MySQL has a connection limit. Adjust connection pool size in URL:

DATABASE_URL="mysql://...?connection_limit=5"

JSON Support

MySQL 5.7+ supports JSON. MariaDB 10.2+ supports JSON (as an alias for LONGTEXT with check constraints). Prisma handles this, but verify your version.