mongodb与sql语句对照表

	SQL Statement		Mongo Statement
	CREATE TABLE USERS (a Number, b Number)		implicit; can also be done explicitlywith 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'});