database

class CreateUserStatsView < ActiveRecord::Migration[6.1]
  def up
    execute <<-SQL
      CREATE VIEW user_stats AS
      SELECT
        users.id AS user_id,

from django.db.models import Q
from django.views.generic import ListView
from .models import Product


class ProductSearchView(ListView):

-- Partition-based archival strategy

-- Create partitioned table
CREATE TABLE logs (
  id BIGSERIAL,
  level VARCHAR(20),

-- Create roles
CREATE ROLE readonly;
CREATE ROLE readwrite;
CREATE ROLE admin WITH LOGIN PASSWORD 'secure_password';

-- Grant permissions to roles

from django.db import transaction
from django.shortcuts import get_object_or_404
from rest_framework import status
from rest_framework.decorators import api_view
from rest_framework.response import Response
from .models import Order, OrderItem, Product

-- Basic transaction
BEGIN;

UPDATE accounts SET balance = balance - 100 WHERE id = 1;
UPDATE accounts SET balance = balance + 100 WHERE id = 2;

package com.example.demo.repository;

import com.example.demo.model.User;
import org.springframework.data.jpa.domain.Specification;

import javax.persistence.criteria.Predicate;

<?php

namespace Database\Seeders;

use Illuminate\Database\Seeder;

-- PostgreSQL Declarative Partitioning (10+)

-- Create partitioned table by date range
CREATE TABLE measurements (
  id BIGSERIAL,
  sensor_id INT NOT NULL,

-- Primary key (unique, not null identifier)
CREATE TABLE users (
  id SERIAL PRIMARY KEY,
  username VARCHAR(50) NOT NULL,
  email VARCHAR(100) NOT NULL
);

module ExistenceChecks
  extend ActiveSupport::Concern

  class_methods do
    def has_any?(conditions = {})
      relation = conditions.present? ? where(conditions) : all

-- Enable pg_stat_statements extension
CREATE EXTENSION IF NOT EXISTS pg_stat_statements;

-- postgresql.conf:
-- shared_preload_libraries = 'pg_stat_statements'
-- pg_stat_statements.track = all