Drizzle ORM - Select parent rows with at least one related child row

Drizzle | Select parent rows with at least one related child row

PostgreSQL

MySQL

SQLite

This guide assumes familiarity with:

Get started with PostgreSQL, MySQL and SQLite
Select statement and select from subquery
Inner join
Filter operators and exists function

This guide demonstrates how to select parent rows with the condition of having at least one related child row. Below, there are examples of schema definitions and the corresponding database data:

import { integer, pgTable, serial, text } from 'drizzle-orm/pg-core';

export const users = pgTable('users', {
  id: serial('id').primaryKey(),
  name: text('name').notNull(),
  email: text('email').notNull(),
});

export const posts = pgTable('posts', {
  id: serial('id').primaryKey(),
  title: text('title').notNull(),
  content: text('content').notNull(),
  userId: integer('user_id').notNull().references(() => users.id),
});

users.db

posts.db

+----+------------+----------------------+
| id |    name    |        email         |
+----+------------+----------------------+
|  1 | John Doe   | [email protected]   |
+----+------------+----------------------+
|  2 | Tom Brown  | [email protected]  |
+----+------------+----------------------+
|  3 | Nick Smith | [email protected] |
+----+------------+----------------------+

+----+--------+-----------------------------+---------+
| id | title  |          content            | user_id |
+----+--------+-----------------------------+---------+
|  1 | Post 1 | This is the text of post 1  |       1 |
+----+--------+-----------------------------+---------+
|  2 | Post 2 | This is the text of post 2  |       1 |
+----+--------+-----------------------------+---------+
|  3 | Post 3 | This is the text of post 3  |       3 |
+----+--------+-----------------------------+---------+

To select parent rows with at least one related child row and retrieve child data you can use .innerJoin() method:

import { eq } from 'drizzle-orm';
import { users, posts } from './schema';

const db = drizzle(...);

await db
  .select({
    user: users,
    post: posts,
  })
  .from(users)
  .innerJoin(posts, eq(users.id, posts.userId));
  .orderBy(users.id);

select users.*, posts.* from users
  inner join posts on users.id = posts.user_id
  order by users.id;

// result data, there is no user with id 2 because he has no posts
[
  {
    user: { id: 1, name: 'John Doe', email: '[email protected]' },
    post: {
      id: 1,
      title: 'Post 1',
      content: 'This is the text of post 1',
      userId: 1
    }
  },
  {
    user: { id: 1, name: 'John Doe', email: '[email protected]' },
    post: {
      id: 2,
      title: 'Post 2',
      content: 'This is the text of post 2',
      userId: 1
    }
  },
  {
    user: { id: 3, name: 'Nick Smith', email: '[email protected]' },
    post: {
      id: 3,
      title: 'Post 3',
      content: 'This is the text of post 3',
      userId: 3
    }
  }
]

To only select parent rows with at least one related child row you can use subquery with exists() function like this:

import { eq, exists, sql } from 'drizzle-orm';

const sq = db
  .select({ id: sql`1` })
  .from(posts)
  .where(eq(posts.userId, users.id));

await db.select().from(users).where(exists(sq));

select * from users where exists (select 1 from posts where posts.user_id = users.id);

// result data, there is no user with id 2 because he has no posts
[
  { id: 1, name: 'John Doe', email: '[email protected]' },
  { id: 3, name: 'Nick Smith', email: '[email protected]' }
]

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