MongoDB语法                                   MySql语法  
db.test.find({‘name‘:‘foobar‘}) <==> select * from test where name=‘foobar‘  
db.test.find()                            <==> select * from test  
db.test.find({‘ID‘:10}).count() <==> select count(*) from test where ID=10  
db.test.find().skip(10).limit(20) <==> select * from test limit 10,20  
db.test.find({‘ID‘:{$in:[25,35,45]}}) <==> select * from test where ID in (25,35,45)  
db.test.find().sort({‘ID‘:-1})  <==> select * from test order by ID desc  
db.test.distinct(‘name‘,{‘ID‘:{$lt:20}})  <==> select distinct(name) from test where ID<20  
  
db.test.group({key:{‘name‘:true},cond:{‘name‘:‘foo‘},reduce:function(obj,prev){prev.msum+=obj.marks;},initial:{msum:0}})  <==> select name,sum(marks) from test group by name  
  
db.test.find(‘this.ID<20‘,{name:1})  <==> select name from test where ID<20  
  
db.test.insert({‘name‘:‘foobar‘,‘age‘:25})<==>insert into test (‘name‘,‘age‘) values(‘foobar‘,25)  
  
db.test.remove({})                        <==> delete * from test  
db.test.remove({‘age‘:20})            <==> delete test where age=20  
db.test.remove({‘age‘:{$lt:20}})   <==> elete test where age<20  
db.test.remove({‘age‘:{$lte:20}})  <==> delete test where age<=20  
db.test.remove({‘age‘:{$gt:20}})  <==> delete test where age>20  
db.test.remove({‘age‘:{$gte:20}}) <==> delete test where age>=20  
db.test.remove({‘age‘:{$ne:20}})  <==> delete test where age!=20  
  
db.test.update({‘name‘:‘foobar‘},{$set:{‘age‘:36}}) <==> update test set age=36 where name=‘foobar‘  
db.test.update({‘name‘:‘foobar‘},{$inc:{‘age‘:3}}) <==> update test set age=age+3 where name=‘foobar‘