Mongodb对应sql操作

SQL Statement
Mongo Statement
CREATE TABLE USERS (a Number, b Number)
implicit; can also be done explicitly with
db.createCollection("mycoll")
ALTER TABLE users ADD ...
implicit

INSERT INTO USERS VALUES(3,5)
db.users.insert({a:3,b:5})

SELECT a,b FROM users
db.users.find({}, {a:1,b:1})
SELECT * FROM users
db.users.find()
SELECT * FROM users WHERE age=33
db.users.find({age:33})
SELECT a,b FROM users WHERE age=33
db.users.find({age:33}, {a:1,b:1})
SELECT * FROM users WHERE age=33 ORDER BY name
db.users.find({age:33}).sort({name:1})
SELECT * FROM users WHERE age>33
db.users.find({age:{$gt:33}})
SELECT * FROM users WHERE age!=33
db.users.find({age:{$ne:33}})
SELECT * FROM users WHERE name LIKE "%Joe%"
db.users.find({name:/Joe/})
SELECT * FROM users WHERE name LIKE "Joe%"
db.users.find({name:/^Joe/})
SELECT * FROM users WHERE age>33 AND age<=40
db.users.find({'age':{$gt:33,$lte:40}})
SELECT * FROM users ORDER BY name DESC
db.users.find().sort({name:-1})
SELECT * FROM users WHERE a=1 and b='q'
db.users.find({a:1,b:'q'})
SELECT * FROM users LIMIT 10 SKIP 20
db.users.find().limit(10).skip(20)
SELECT * FROM users WHERE a=1 or b=2
db.users.find( { $or : [ { a : 1 } , { b : 2 } ] } )
SELECT * FROM users LIMIT 1
db.users.findOne()
SELECT order_id FROM orders o, order_line_items li WHERE li.order_id=o.order_id AND li.sku=12345
db.orders.find({"items.sku":12345},{_id:1})
SELECT customer.name FROM customers,orders WHERE orders.id="q179" AND orders.custid=customer.id
var o = db.orders.findOne({_id:"q179"});
var name = db.customers.findOne({_id:o.custid})

SELECT DISTINCT last_name FROM users
db.users.distinct('last_name')
SELECT COUNT(*y)
FROM users
db.users.count()
SELECT COUNT(*y)
FROM users where AGE > 30
db.users.find({age: {'$gt': 30}}).count()
SELECT COUNT(AGE) from users
db.users.find({age: {'$exists': true}}).count()

CREATE INDEX myindexname ON users(name)
db.users.ensureIndex({name:1})
CREATE INDEX myindexname ON users(name,ts DESC)
db.users.ensureIndex({name:1,ts:-1})

EXPLAIN SELECT * FROM users WHERE z=3
db.users.find({z:3}).explain()

UPDATE users SET a=1 WHERE b='q'
db.users.update({b:'q'}, {$set:{a:1}}, false, true)
UPDATE users SET a=a+2 WHERE b='q'
db.users.update({b:'q'}, {$inc:{a:2}}, false, true)

DELETE FROM users WHERE z="abc"
db.users.remove({z:'abc'});