database

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),

<?php

use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;

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,

import random


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

from django.db.models import Prefetch
from django.views.generic import ListView
from .models import Post, Comment


class PostListView(ListView):

from django.db import models
from django.utils.text import slugify


class Article(models.Model):
    title = models.CharField(max_length=200)

class CreateCustomerRevenueSummaries < ActiveRecord::Migration[7.0]
  def change
    create_view :customer_revenue_summaries, materialized: true, version: 1

    add_index :customer_revenue_summaries,
              :customer_id,

-- Create basic index
CREATE INDEX idx_users_email ON users(email);

-- Unique index (enforces uniqueness)
CREATE UNIQUE INDEX idx_users_username ON users(username);