sql语法和MongoDB语法的对应关系

SQL Statement	Mongo Query Language Statement
CREATE TABLE USERS (a Number, b Number)	db.createCollection( "mycoll", {capped:true , size:100000})
INSERT INTO USERS VALUES(1,1)	db.users.insert({a:1,b:1})
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':{$gt:33}})})
SELECT * FROM users WHERE age<33	db.users.find({'age':{$lt: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})
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})
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( { $or : [ { a : 1 } , { b : 2 } ] } )
SELECT * FROM users LIMIT 1	db.users.findOne()
EXPLAIN SELECT * FROM users WHERE z=3	db.users.find({z:3}).explain()
SELECT DISTINCT last_name FROM users	db.users.distinct('last_name')
SELECT COUNT(*y) FROM users	db.users.count()
SELECT COUNT(*y) FROM users where AGE > 30	db.users.find({age: {'$gt': 30}}).count()
SELECT COUNT(AGE) from users	db.users.find({age: {'$exists': true}}).count()
UPDATE users SET a=1 WHERE b='q'	db.users.update({b:'q'}, {$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'});