mongodb多表查询(附带pymongo实例)

Posted 2020-10-28 菲菲菲菲菲常新的新手

mongodb有$lookup可以做多表查询

举个例子

db.orders.aggregate([
 {
 $lookup:
 {
  from: "inventory",
  localField: "item",
  foreignField: "sku",
  as: "inventory_docs"
 }
 }
])

上面的代码意思是，从order表中取item字段作为inventory表中sku的查询条件，然后把数据保存到inventory_docs字段

等价于db.inventory.find({‘sku‘:"item"})

下面用pymongo实现

from pymongo import MongoClient

def test():
    client = MongoClient()
    db = client[db_name]
    db[‘orders‘].aggregate([{‘$lookup‘:{‘from‘: "inventory", "localField": "item", "foreignField": "sku", "as": "inventory_docs"}}])

这样就实现了上述的效果了