Python pymongo 方法 查询语句
时间: 2024-08-16 19:04:47 浏览: 46
在Python中,`pymongo`是一个用于操作MongoDB数据库的驱动程序,它提供了一套丰富的API来进行数据查询。以下是一些基本的查询语句:
1. **查找文档** (Find documents):
```python
from pymongo import MongoClient
client = MongoClient('mongodb://localhost:27017/')
db = client['your_database']
collection = db['your_collection']
# 使用find()方法获取所有文档
documents = collection.find()
```
2. **筛选特定条件** (Filter with conditions):
```python
query = {'field': 'value'} # 这里的'field'和'value'是你想要匹配的关键字和值
matching_docs = collection.find(query)
```
3. **分页查询** (Pagination):
```python
skip_count = 0
limit_count = 10 # 每页显示10条
page_docs = collection.find().skip(skip_count).limit(limit_count)
```
4. **聚合查询** (Aggregation) - 对数据进行复杂分析:
```python
pipeline = [
{'$group': {'_id': '$category', 'count': {'$sum': 1}}},
{'$sort': {'count': -1}} # 排序降序
]
result = collection.aggregate(pipeline)
```
5. **查询唯一值或存在性** (Unique values or existence check):
```python
unique_values = collection.distinct('field')
exists = collection.count_documents({'field': 'value'})
```