database

import random


class ReadWriteRouter:
    """Route reads to replicas, writes to primary."""

from blog.models import Post


# Load only specific fields
posts = Post.objects.only('id', 'title', 'published_at')
for post in posts:

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': 'mydb',
        'USER': 'myuser',
        'PASSWORD': 'mypassword',

import { PrismaClient } from '@prisma/client';

const prisma = new PrismaClient();

export async function getFeedNaive(limit = 20) {
  const posts = await prisma.post.findMany({

production:
  primary:
    adapter: postgresql
    database: app_production
    username: app
    password: <%= ENV["PRIMARY_DB_PASSWORD"] %>

-- INNER JOIN: Only matching rows
SELECT
  users.name,
  orders.order_number,
  orders.total
FROM users

import sqlite3

import click
from flask import current_app, g

module ConnectionHealth
  extend ActiveSupport::Concern

  def with_fresh_connection
    conn = ActiveRecord::Base.connection
    conn.verify! # pings and reconnects if the socket is dead

-- Unnormalized (0NF): Repeating groups
CREATE TABLE orders_bad (
  order_id INT,
  customer_name VARCHAR(100),
  customer_email VARCHAR(100),
  product1 VARCHAR(100),

package export

import (
	"encoding/csv"
	"log"
	"net/http"

use sqlx::PgPool;

#[derive(sqlx::FromRow)]
struct User {
    id: i32,
    name: String,

-- Connection statistics
SELECT
  count(*) AS total_connections,
  count(*) FILTER (WHERE state = 'active') AS active,
  count(*) FILTER (WHERE state = 'idle') AS idle,
  count(*) FILTER (WHERE state = 'idle in transaction') AS idle_in_tx,