db.userInfo.find();

select* from userInfo;

db.userInfo.distinct("name");

select disttince name from userInfo;

db.userInfo.find({"age": 22});

select * from userInfo where age = 22;

db.userInfo.find({age: {$gt: 22}});

select * from userInfo where age >22;

db.userInfo.find({age: {$lt: 22}});

select * from userInfo where age <22;

db.userInfo.find({age: {$gte: 25}});

select * from userInfo where age >= 25;

db.userInfo.find({age: {$lte: 25}});

select * from userInfo where age <= 25;

db.userInfo.find({age: {$gte: 23, $lte: 26}});

select * from userInfo where age >=23 and age <= 26;

db.userInfo.find({name: /mongo/});

select * from userInfo where name like ‘%mongo%';

db.userInfo.find({name: /^mongo/});

select * from userInfo where name like ‘mongo%';

db.userInfo.find({}, {name: 1, age: 1});

select name, age from userInfo;

db.userInfo.find({age: {$gt: 25}}, {name: 1, age: 1});

select name, age from userInfo where age >25;

db.userInfo.find().sort({age: 1});

db.userInfo.find().sort({age: -1});

db.userInfo.find().limit(5);

select * from (select * from userInfo) where rownum < 6;//oracle

select * from userInfo limit 5;//mysql

db.userInfo.find().skip(10);

db.userInfo.find().limit(10).skip(5);

db.userInfo.find({$or: [{age: 22}, {age: 25}]});

select * from userInfo where age = 22 or age = 25;

db.userInfo.findOne();

db.userInfo.find().limit(1);

select * from (select * from userInfo) where and rownum < 2

db.userInfo.find({age: {$gte: 25}}).count();

相当于：select count(*) from userInfo where age >= 20;

db.userInfo.ensureIndex({username: 1});

db.userInfo.ensureIndex({username: 1, age: -1});

db.test.find({"age": 30, "username": "stephen"})

db.test.ensureIndex({"userid":1},{"unique":true})

db.test.insert({"userid":5})

db.test.insert({"userid":5})

E11000 duplicate key error index: test.test.$userid_1 dup key: { : 5.0 }

db.test.insert({"userid1":5})

db.test.insert({"userid1":5})

E11000 duplicate key error index: test.test.$userid_1 dup key: { : null }

db.test.dropIndex({"userid":1})

db.test.remove()

db.test.insert({"userid":5})

db.test.insert({"userid":5})

db.test.ensureIndex({"userid":1},{"unique":true,"dropDups":true})

db.test.find()

{ "_id" : ObjectId("4fe823c180144abd15acd52e"), "userid" : 5 }

db.test.ensureIndex({"userid":1,"age":1},{"unique":true})

db.userInfo.getIndexes();

db.userInfo.totalIndexSize();

db.users.reIndex();

db.users.dropIndex("username":1);

db.users.dropIndexes();