Seeding Test Databases with Sample Data — SQL, JSON, CSV

Every development and staging environment needs realistic seed data. This guide shows how to seed databases using sample SQL, JSON, and CSV files from TrueFileSize — with examples for PostgreSQL, MySQL, SQLite, MongoDB, and ORMs.

Step 1: Download Sample Data

mkdir -p seed-data
CDN="https://cdn.truefilesize.com"

# SQL dump (CREATE TABLE + INSERT statements)
curl -sL -o seed-data/users.sql "$CDN/sql/sample-users.sql"

# JSON data (realistic user records)
curl -sL -o seed-data/users.json "$CDN/json/sample-users.json"
curl -sL -o seed-data/products.json "$CDN/json/sample-products.json"

# CSV data (tabular import)
curl -sL -o seed-data/users.csv "$CDN/csv/sample-users.csv"

# SQLite database (pre-seeded)
curl -sL -o seed-data/dev.sqlite "$CDN/sqlite/sample-1mb.sqlite"

Available: SQL · JSON · CSV · SQLite

PostgreSQL

# Import SQL dump directly
psql -U postgres -d myapp_dev < seed-data/users.sql

# Import CSV into existing table
psql -U postgres -d myapp_dev -c "\
  COPY users(name, email, city, date) \
  FROM '/path/to/seed-data/users.csv' \
  WITH CSV HEADER;"

# Import JSON using psql + jq
cat seed-data/users.json | jq -c '.[]' | while read row; do
  psql -U postgres -d myapp_dev -c "INSERT INTO users (data) VALUES ('$row'::jsonb);"
done

MySQL

# Import SQL dump
mysql -u root -p myapp_dev < seed-data/users.sql

# Import CSV
mysql -u root -p myapp_dev -e "
  LOAD DATA LOCAL INFILE 'seed-data/users.csv'
  INTO TABLE users
  FIELDS TERMINATED BY ','
  ENCLOSED BY '\"'
  LINES TERMINATED BY '\n'
  IGNORE 1 ROWS;"

SQLite

# Use pre-seeded SQLite database directly
cp seed-data/dev.sqlite ./prisma/dev.db

# Or import SQL
sqlite3 dev.db < seed-data/users.sql

# Import CSV
sqlite3 dev.db <<EOF
.mode csv
.import seed-data/users.csv users
EOF

Download sample SQLite databases with multi-table schemas already populated.

MongoDB

# Import JSON array as collection
mongoimport --db myapp_dev --collection users \
  --jsonArray --file seed-data/users.json

# Import CSV
mongoimport --db myapp_dev --collection users \
  --type csv --headerline --file seed-data/users.csv

Node.js with Prisma

// prisma/seed.ts
import { PrismaClient } from '@prisma/client';
import users from '../seed-data/users.json';
import products from '../seed-data/products.json';

const prisma = new PrismaClient();

async function seed() {
  // Clear existing data
  await prisma.user.deleteMany();
  await prisma.product.deleteMany();

  // Seed users
  for (const user of users) {
    await prisma.user.create({
      data: {
        name: user.name,
        email: user.email,
        age: user.age,
        city: user.city,
        active: user.active,
      },
    });
  }

  // Seed products
  for (const product of products) {
    await prisma.product.create({
      data: {
        name: product.name,
        price: product.price,
        category: product.category,
        inStock: product.inStock,
      },
    });
  }

  console.log(`Seeded ${users.length} users, ${products.length} products`);
}

seed()
  .catch(console.error)
  .finally(() => prisma.$disconnect());

Add to package.json:

{
  "prisma": {
    "seed": "tsx prisma/seed.ts"
  }
}

Run: npx prisma db seed

Python with SQLAlchemy

import json
import csv
from sqlalchemy import create_engine, text

engine = create_engine('postgresql://localhost/myapp_dev')

# Seed from JSON
with open('seed-data/users.json') as f:
    users = json.load(f)

with engine.begin() as conn:
    for user in users:
        conn.execute(text("""
            INSERT INTO users (name, email, age, city, active)
            VALUES (:name, :email, :age, :city, :active)
        """), user)

print(f"Seeded {len(users)} users")

CI/CD Integration

Add seeding to your test pipeline:

# .github/workflows/test.yml
- name: Download seed data
  run: |
    mkdir -p seed-data
    curl -sL -o seed-data/users.json https://cdn.truefilesize.com/json/sample-users.json
    curl -sL -o seed-data/products.json https://cdn.truefilesize.com/json/sample-products.json

- name: Seed database
  run: npx prisma db seed

- name: Run tests
  run: npm test

See our full CI/CD guide for caching and parallel jobs.

Sample Data Available

| Data Type | File | Records | Size | |-----------|------|---------|------| | Users (JSON) | sample-users.json | 500 | 77 KB | | Products (JSON) | sample-products.json | 500 | 111 KB | | Users (CSV) | sample-users.csv | 1,000+ | 50 KB | | SQL Dump | sample-users.sql | Various | 50 KB | | SQLite (pre-seeded) | sample-1mb.sqlite | 500+ | 1 MB | | Large dataset | sample-10000-records.json | 10,000 | 1.5 MB |

All data is generated with faker.js — realistic names, emails, cities, and dates. No real personal information.