# 獲取所有電影對(duì)象（避免內(nèi)存溢出）
films = Film.objects.all()

# 使用迭代器處理大規(guī)模數(shù)據(jù) 
for film in films.iterator(chunk_size=1000):
    # 處理每個(gè)電影對(duì)象
    print(film.title)

# 獲取2023年上映的電影
films_2023 = Film.objects.filter(year=2023)

# 獲取評(píng)分大于4.0的電影
high_rated_films = Film.objects.filter(rating__gt=4.0)

# 只獲取需要的字段
film_titles = Film.objects.values_list('title', flat=True)

# 獲取特定字段組合
film_data = Film.objects.values('id', 'title', 'year')

# 使用select_related優(yōu)化外鍵查詢
films = Film.objects.select_related('studio').all()

# 使用prefetch_related優(yōu)化多對(duì)多關(guān)系
films = Film.objects.prefetch_related('actors').all()

# 獲取特定ID集合的電影
film_ids = [101, 205, 307, 409]
films = Film.objects.in_bulk(film_ids, field_name='id')

# 使用結(jié)果
film_205 = films[205]

from django.core.paginator import Paginator

# 每頁(yè)100條記錄
paginator = Paginator(Film.objects.all(), 100)

for page_num in range(1, paginator.num_pages + 1):
    page = paginator.page(page_num)
    for film in page.object_list:
        # 處理每部電影
        process_film(film)

# 創(chuàng)建多個(gè)電影對(duì)象
films_to_create = [
    Film(title="電影A", year=2023),
    Film(title="電影B", year=2022),
    Film(title="電影C", year=2021)
]

# 批量創(chuàng)建（返回創(chuàng)建的對(duì)象列表）
created_films = Film.objects.bulk_create(films_to_create)

# 批量更新評(píng)分
films_to_update = Film.objects.filter(year=2023)
for film in films_to_update:
    film.rating = 4.5  # 更新評(píng)分

# 批量更新到數(shù)據(jù)庫(kù)
Film.objects.bulk_update(films_to_update, ['rating'])

# 刪除所有2020年之前的電影
Film.objects.filter(year__lt=2020).delete()

# 只加載必要字段
films = Film.objects.only('title', 'year')

# 排除大字段
films = Film.objects.defer('plot')

# 批量添加演員
film = Film.objects.get(id=101)
actors_to_add = Actor.objects.filter(id__in=[1, 2, 3])
film.actors.add(*actors_to_add)

# 批量移除演員
film.actors.remove(*actors_to_add)

from django.db import connection

def bulk_update_ratings():
    with connection.cursor() as cursor:
        cursor.execute("""
            UPDATE film_information
            SET rating = rating * 1.1
            WHERE year >= 2020
        """)

def update_film_ratings():
    # 獲取需要更新的電影
    films = Film.objects.filter(year__gte=2020)
    
    # 批量更新評(píng)分
    for film in films:
        film.rating = calculate_new_rating(film)
    
    # 批量提交到數(shù)據(jù)庫(kù)
    Film.objects.bulk_update(films, ['rating'], batch_size=500)

def import_films_from_csv(csv_path):
    import csv
    films_to_create = []
    
    with open(csv_path, 'r', encoding='utf-8') as f:
        reader = csv.DictReader(f)
        for row in reader:
            films_to_create.append(Film(
                title=row['title'],
                year=int(row['year']),
                # ...其他字段
            ))
    
    # 分批次創(chuàng)建（每批1000條）
    batch_size = 1000
    for i in range(0, len(films_to_create), batch_size):
        batch = films_to_create[i:i+batch_size]
        Film.objects.bulk_create(batch)

def process_film_tags():
    # 獲取所有電影及其標(biāo)簽
    films = Film.objects.prefetch_related('tags')
    
    for film in films:
        # 處理每個(gè)電影的標(biāo)簽
        tags_to_add = calculate_new_tags(film)
        film.tags.add(*tags_to_add)
        
        # 移除不需要的標(biāo)簽
        tags_to_remove = get_obsolete_tags(film)
        film.tags.remove(*tags_to_remove)

from django.db import transaction

with transaction.atomic():
    # 批量操作代碼
    Film.objects.bulk_create(films)

try:
    Film.objects.bulk_update(films, ['rating'])
except Exception as e:
    logger.error(f"批量更新失敗: {str(e)}")
    # 回退或重試邏輯

from django.db import connection

print(connection.queries)  # 查看執(zhí)行的SQL查詢