Django ORM

# models.py from django.db import models class Post(models.Model): title = models.CharField(max_length=100) content = models.TextField() created_at = models.DateTimeField(auto_now_add=True) def __str__(self): return self.title

python manage.py makemigrations python manage.py migrate

post = Post.objects.create(title='첫 글', content='장고 ORM 시작!')

Post.objects.all() # 전체 조회 Post.objects.get(id=1) # 단일 조회 Post.objects.filter(title='첫 글') # 조건 조회

post = Post.objects.get(id=1) post.title = '수정된 제목' post.save()

post = Post.objects.get(id=1) post.delete()

# admin.py from .models import Post admin.site.register(Post)

python manage.py createsuperuser

class Comment(models.Model): post = models.ForeignKey(Post, on_delete=models.CASCADE) content = models.TextField() created_at = models.DateTimeField(auto_now_add=True)

# 댓글 추가 post = Post.objects.get(id=1) post.comment_set.create(content="댓글입니다")

# 예시 Post.objects.values('title', 'created_at') # title과 created_at 필드만 조회

# 작성자별 게시글 수 계산 from django.db.models import Count Post.objects.values('author').annotate(post_count=Count('id')) # 카테고리별 평균 조회수 계산 from django.db.models import Avg Post.objects.values('category').annotate(avg_views=Avg('views'))

Post.objects.filter(title__contains="장고")

SELECT * FROM post WHERE title LIKE '%장고%';

Post.objects.exclude(title__contains="테스트")

SELECT * FROM post WHERE title NOT LIKE '%테스트%';

Post.objects.order_by('-created_at')

SELECT * FROM post ORDER BY created_at DESC;

Post.objects.order_by('-created_at', 'title')

SELECT * FROM post ORDER BY created_at DESC title ASC ;

Post.objects.count()

SELECT COUNT(*) FROM post ;

from django.db.models import Count Post.objects.values('writer').annotate(post_count=Count('*'))

SELECT writer, COUNT(*) AS post_count FROM post GROUP BY writer ;

Post.objects.filter(id=3).exists()

SELECT 1 FROM post WHERE id = 3 LIMIT 1 ;

Post.objects.values('title')

SELECT title FROM post ;

[ {'title': '장고 입문'}, {'title': 'Python 기초'}, {'title': '게시판 만들기'}, ... ]