MongoDB Learning Three

This chapter we learn about MongoDB query operations.

Introduction to find

The Find method is used to perform the query operation of MongoDB. It returns a subset of documents in Collecion, which returns the entire collection data without adding parameters.

Example: Finding all the data for C

Db.c.find ()

The first parameter of find is the query condition, which determines which documents data is returned.

Example: We want to find the user with age 27 in the user table

Db.users.find ({"Age": 27})

What if we want a multi-conditional query? Just continue adding the condition in the first parameter:

Db.users.find ({"Age": +, "username": "Joe"})

Specifying which Keys to Return

Cond...

MongoDB Learning Three