MongoDB Database and MySQL operation

On the left is the MONGODB query statement, and the right is the SQL statement. Compared with the use, very convenient.

Db.users.find () SELECT * from Users

Db.users.find ({"Age": +}) SELECT * from the users where age = 27

Db.users.find ({"username": "Joe", "Age": +}) SELECT * from the users where "username" = "Joe" and age = 27

Db.users.find ({}, {"username": 1, "email": 1}) Select Username, email from users

Db.users.find ({}, {"username": 1, "_id": 0})//No case// Instant column filter is added,_id will also return; must explicitly block _id return

Db.users.find ({"Age": {"$gte": +, "$lte": ()}) select * from the users where age >=18 and age <=//$lt (<) $l Te (<=) $gt (>) $gte (>=)

Db.users.find ({"username": {"$ne": "Joe"}}) select * from users where username <> "Joe"

Db.users.find ({"Ticket_no": {"$in": [725, 542, 390]}) SELECT * from the users where Ticket_no in (725, 542, 390)

Db.users.find ({"Ticket_no": {"$nin": [725, 542, 390]}) SELECT * from the users where ticket_no not in (725, 542, 390)

Db.users.find ({"$or": [{"Ticket_no": 725}, {"Winner": True}]}) select * Form users where Ticket_no = 725 or winner = TR Ue

Db.users.find ({"Id_num": {"$mod": [5, 1]}}) select * from Users where (id_num mod 5) = 1

Db.users.find ({"$not": {"Age": +}}) select * from the users where not (age = 27)

Db.users.find ({"username": {"$in": [null], "$exists": True}}) select * from the users where username is null// if directly through the /c0>Find ({"username": null}) for query, then the " no username" record is filtered out

Db.users.find ({"Name":/joey?/i})// regular query,value is an expression that conforms to PCRE

Db.food.find ({fruit: {$all: ["Apple", "Banana"]}})// array of Queries , field fruit , contains both "Apple" with a record of "Banana"

db.food.find ({"fruit.2"  :  "Peach"})//  query for array Span style= "Font-family:times New Roman" >,&NBSP; field fruit 3 from 0 Start element is peach

db.food.find ({"Fruit"  : {"$size"  : 3}})//  Query for arrays ,&NBSP; query array element number is 3 Records, $size Front cannot be combined with other operators

Db.users.findOne (criteria, {"Comments": {"$slice":})//array of queries, returning only the first 10 of the arrays comments , can also {"$slice": -10}, {"$slice": [Max]}; return the last Ten Bar, and the middle Ten Strip

Db.people.find ({"Name.first": "Joe", "Name.last": "Schmoe"})// nested query

Db.blog.find ({"Comments": {"$elemMatch": {"author": "Joe", "score": {"$gte": 5}}})// nested query only when nested elements are arrays using ,

Db.foo.find ({"$where": "this.x + This.y = ="})// complex queries,$where of course are very convenient, but inefficient. For complex queries, the order of consideration should be regular---MapReduce-- $where

Db.foo.find ({"$where": "function () {return this.x + This.y = = Ten;}"})//$where can support JavaScript functions as Query Criteria

Db.foo.find (). Sort ({"X": 1}). Limit (1). Skip (10); return to paragraph (ten, one), by "x" to sort ; three x Limit The order is arbitrary, should try to avoid Skip used in Large-number

MongoDB Database and MySQL operation