ORM basics
An ORM maps database tables to JavaScript objects so you write less raw SQL.
In this page:
Syntax
const Model = sequelize.define('ModelName', {
field: DataTypes.TYPE
});
const records = await Model.findAll();ORM basics
Object-relational mappers such as Sequelize, Prisma and TypeORM define models in code and generate queries. They speed up development, offer migrations and validation, but can hide costly queries. Learn the SQL they generate for performance work.
Note:
Log generated SQL in development to catch N+1 queries.
Example: ORM basics
const { Sequelize, DataTypes } = require("sequelize");
const db = new Sequelize("sqlite::memory:");
const User = db.define("User", { name: DataTypes.STRING, age: DataTypes.INTEGER });
await db.sync();
await User.create({ name: "Ada", age: 36 });
console.log((await User.findAll({ where: { age: 36 } })).length);⚠️ Run this in your own terminal or Node.js environment.
Related Topics
Common Mistakes
- Ignoring generated SQL
- N+1 query problems
- Treating an ORM as a replacement for understanding SQL
Chapter Summary
- ORMs map tables to objects
- Popular: Prisma, Sequelize, TypeORM
- They generate SQL
- Watch for N+1 queries
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