Django ORM? django? ?? ??? ?? ? ?????. ?? ???????? ?? ??? ???? ?? ?? ????? ???? ?? SQL? ?? Python ??? ???? ???? ??? ? ?? ????. ??? ?? ORM ??? ?? ?? ???? ??? ?? ??? ??? ? ?? SQL ??? ?????.
? ?????? Django ORM? ??? ? ?? ???? ??? ???? ??? ????? ?? ?? ???? ?? ?? ???? ?? ?? ?????.

1. N 1 ?? ??

N 1 ?? ??? ??? ??? ??? ????? ??? ??? ??? ?? N?? ?? ??? ?? ???? ?? ???? ??? ? ?????.

blogs = Blog.objects.all()    # 1 Query
for blog in blogs:
    print(blog.author.name)   # N additional queries

?? ??? ?? ??? blog.author.name? ????? Django? ? ???? ??? ???? ????? ???? N?? ?? ??? ?????.

?? ??
?? ?? ??(?: ForeignKey ?? OneToOneField)? ?? select_??? ?????. SQL JOIN? ???? ??? ???? ?? ??? ?? ??? ???? ?????. ???, ??? ?? ???? ?? ?? ???? ??? ??? ????? Python?? ????? ???? N 1 ??? ???? prefetch_??? ?????.

# With select_related
blogs = Blog.objects.select_related('author').all()

# With prefetch_related
authors = Author.objects.prefetch_related('blogs').all()

2. .all() ? .filter()? ??

???? ?? ?? ??? ????? .all()? ???? ??? ?? ??? ?? ?? ??? ?????.

blogs = Blog.objects.all()
active_blogs = blogs.filter(is_archived=False)
popular_blogs = blogs.filter(views__gte=1000)

Django? ??? ?? ?? ???? ?? ??? ?????? ????? ??? ?? ?? ???? ?? ??? ????? ???? ??? ??????? ???? ??? ??? ? ????.

?? ??
??? ???? ??? ???? django? ?? SQL ??? ??? ? ????.

popular_active_blogs = Blog.objects.filter(is_archived=False, views__gte=1000)

3. value() ?? value_list()? ???? ??

??? ?? ?? ???? ?? ?? ??? ??? ??? ????. ? ?? .values() ?? .values_list()? ???? ?? ? ???? ? ????.

titles = Blog.objects.values('title')
or
titles = Blog.objects.values_list('title', flat=True)
# values() returns a list of dictionaries.
# values_list() can return tuples or flat values if flat=True is provided.

??? ?? ???? ???????? ???? ???? ?? ???? ??? ?????.

4. ????? ?? ? ??

.aggregate() ?? .annotate()? ????? ???? ?? ??? ??? ? ????. ?? ??? ??? ??? ??? ????? SQL ??? ??? ? ???, ?? ??? ?????? ???? ??? ? ????.

# Example of multiple aggregate
total_count = Blog.objects.aggregate(Count('id'))
author_count = Blog.objects.aggregate(Count('author'))
average_views = Blog.objects.aggregate(Avg('views'))

??

blogs = Blog.objects.all()    # 1 Query
for blog in blogs:
    print(blog.author.name)   # N additional queries

5. ?????? ???? ???? ??

???? ??????? ???? ???? ?? ??? ? ??? ?? ?? ??? ????? ?? ?? ??? ??? ?????. ???? ???, ??, ??? ?? ??? ????? ?? ????? ??? ?? ??? ?? ??? ????. ?? ???? ??? ?????? ???? ??? ??? ?? ??? ? ????.
Django?? ???? ???? ??

# With select_related
blogs = Blog.objects.select_related('author').all()

# With prefetch_related
authors = Author.objects.prefetch_related('blogs').all()

??? ?? ??? ?? ? ??? ?? ??? ?? ? ????. ??? ?? ???? ?? ??? ??????.

6. ??? ???? ??

?? ??? ?? ??? ?? ???? ?? ???? ???? ?? ?? ??? ?????. 5???? ???? ?? ??, ??? ??, ?? ???? ?? ??? ?? ? ????.

blogs = Blog.objects.all()
active_blogs = blogs.filter(is_archived=False)
popular_blogs = blogs.filter(views__gte=1000)

7. ?? SQL

Django ORM? ??? ??? ?? ??? ????? ???? ??? ??? ????. Django? .extra() ?? .raw()? ????? ?? SQL ??? ??? ?? ??? ??? ??? ??? ???.

• ORM? ?? ?? ??
• ?? ? ??? ??? ???? ?? ??? ??? ? ????

??? ???? ???? ?? SQL ??? ?? ??? ? ??? ?????.

??? ?? ???? ??? ???? ?? ???? ?? ????? Django ?? ??? ??? ? ????. ?? ?? ???? Django ??? ??? ???? ??? ?? ?, ?? ?? ? SQL ?? ?????? ???? ?? ????.

? ??? ???? ? ???? Django ORM ??? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!