In MongoDB we use the find() and find_one() methods to find data in a collection.
Just like the SELECT statement is used to find data in a table in a MySQL database.
Find One #
To select data from a collection in MongoDB, we can use the find_one() method.
The find_one() method returns the first occurrence in the selection.
Example – Жишээ #
Find the first document in the customers collection:
import pymongo
myclient = pymongo.MongoClient("mongodb://localhost:27017/")
mydb = myclient["mydatabase"]
mycol = mydb["customers"]
x = mycol.find_one()
print(x)
Find All – #
To select data from a table in MongoDB, we can also use the find() method.
The find() method returns all occurrences in the selection.
The first parameter of the find() method is a query object. In this example we use an empty query object, which selects all documents in the collection.
No parameters in the find() method gives you the same result as SELECT * in MySQL.
find() арга параметргүй үед MySQL-д ашигладаг SELECT * командтай адил үр дүнг авах болно.
Example – Жишээ #
Return all documents in the “customers” collection, and print each document:
import pymongo
myclient = pymongo.MongoClient("mongodb://localhost:27017/")
mydb = myclient["mydatabase"]
mycol = mydb["customers"]
for x in mycol.find():
print(x)
Return Only Some Fields – Зөвхөн зарим талбаруудыг буцаах #
The second parameter of the find() method is an object describing which fields to include in the result.
This parameter is optional, and if omitted, all fields will be included in the result.
Example – Жишээ #
Return only the names and addresses, not the _ids:
Зөвхөн нэрнүүд болон хаягнуудыг буцаана уу, _ids орохгүйгээр:
import pymongo
myclient = pymongo.MongoClient("mongodb://localhost:27017/")
mydb = myclient["mydatabase"]
mycol = mydb["customers"]
for x in mycol.find({},{ "_id": 0, "name": 1, "address": 1 }):
print(x)
You are not allowed to specify both 0 and 1 values in the same object (except if one of the fields is the _id field). If you specify a field with the value 0, all other fields get the value 1, and vice versa:
Example – Жишээ #
This example will exclude “address” from the result:
Энэ жишээний үр дүн нь “хаяг”-г хасна:
import pymongo
myclient = pymongo.MongoClient("mongodb://localhost:27017/")
mydb = myclient["mydatabase"]
mycol = mydb["customers"]
for x in mycol.find({},{ "address": 0 }):
print(x)
Example #
You get an error if you specify both 0 and 1 values in the same object (except if one of the fields is the _id field):
import pymongo
myclient = pymongo.MongoClient("mongodb://localhost:27017/")
mydb = myclient["mydatabase"]
mycol = mydb["customers"]
for x in mycol.find({},{ "name": 1, "address": 0 }):
print(x)
