mongodb 3

作用	SQL	mongdb
所有记录	SELECT * FROM users	db.users.find()
age=33的记录	SELECT * FROM users WHERE age=33	db.users.find({age:33})
子键（字段）筛选	SELECT a, b FROM users WHERE age=33	db.users.find({age:33}, {a:1,b:1})
排序	SELECT * FROM users WHERE age=33 ORDER BY name	db.users.find({age:33}).sort({name:1})
比大小	SELECT * FROM users WHERE age>33	db.users.find({'age':{$gt:33}})})
正则（模糊匹配）	SELECT * FROM users WHERE name LIKE "Joe%"	db.users.find({name:/^Joe/})
忽略、限制	SELECT * FROM users LIMIT 10 SKIP 20	db.users.find().limit(10).skip(20)
Or操作	SELECT * FROM users WHERE a=1 or b=2	db.users.find( { $or : [ { a : 1 } , { b : 2 } ] } )
仅返回1条(TOP 1)	SELECT * FROM users LIMIT 1	db.users.findOne()
Distinct聚合	SELECT DISTINCT last_name FROM users	db.users.distinct('last_name')
Count聚合	SELECT COUNT(AGE) from users	db.users.find({age: {'$exists': true}}).count()
查询计划	EXPLAIN SELECT * FROM users WHERE z=3	db.users.find({z:3}).explain()
引用自：http://www.mongodb.org/display/DOCS/SQL+to+Mongo+Mapping+Chart