MongoDB与MySQL语法等对比

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'

1、完整语法对比

看看语法先：

查询：

MySQL:

SELECT * FROM user

Mongo:

db.user.find()

带条件的查询:

MySQL:

SELECT * FROM user WHERE name = ’starlee’

Mongo:

db.user.find({‘name’ : ’starlee’})

插入：

MySQL:

INSERT INOT user (`name`, `age`) values (’starlee’,25)

Mongo:

db.user.insert({‘name’ : ’starlee’, ‘age’ : 25})

如果你想在MySQL里添加一个字段，你必须：

ALTER TABLE user….

但在MongoDB里你只需要：

db.user.insert({‘name’ : ’starlee’, ‘age’ : 25, ‘email’ : ’starlee@starlee.com’})

删除：

MySQL:

DELETE * FROM user

Mongo:

db.user.remove({})

带条件的删除:

MySQL:

DELETE FROM user WHERE age < 30

Mongo:

db.user.remove({‘age’ : {$lt : 30}})

MongoDB中的大小比较符号:

$gt : >

$gte : >=

$lt : <

$lte : <=

$ne : !=

UPDATE更新:

MySQL:

UPDATE user SET `age` = 36 WHERE `name` = ’starlee’

Mongo:

db.user.update({‘name’ : ’starlee’}, {$set : {‘age’ : 36}})

带有运算的更新:

MySQL:

UPDATE user SET `age` = `age` + 3 WHERE `name` = ’starlee’

Mongo:

db.user.update({‘name’ : ’starlee’}, {$inc : {‘age’ : 3}})

count求总数:

MySQL:

SELECT COUNT(*) FROM user WHERE `name` = ’starlee’

Mongo:

db.user.find({‘name’ : ’starlee’}).count()

也可以写成这样:

db.user.count({‘name’:’starlee’})

LIMIT子句:

MySQL:

SELECT * FROM user limit 10,20

Mongo:

db.user.find().skip(10).limit(20)

IN子句:

MySQL:

SELECT * FROM user WHERE `age` IN (25, 35,45)

Mongo:

db.user.find({‘age’ : {$in : [25, 35, 45]}})

Order排序:（1表示正序，-1逆序）

MySQL:

SELECT * FROM user ORDER BY age DESC

Mongo:

db.user.find().sort({‘age’ : -1})

Distinct排重:

MySQL:

SELECT DISTINCT(name) FROM user WHERE age > 20

Mongo:

db.user.distinct(‘name’, {‘age’: {$lt : 20}})

Group 分组:

MySQL:

SELECT name, sum(marks) FROM user where name=’foo’ GROUP BY name

Mongo:

db.user.group({

key : {‘name’ : true},

cond: {‘name’ : ‘foo’},

reduce: function(obj,prev) { prev.msum += obj.marks; },

initial: {msum : 0}

});

获取age字段小于20的数据的name字段

MySQL:

SELECT name FROM user WHERE age < 20

Mongo:

db.user.find(‘this.age < 20′, {name : 1})

循环插入数据:

for(var i=0;i<100;i++)db.user.insert({uid:i,uname:’nosqlfan’+i});

这样一次性插入了一百条数据

{ “_id” : ObjectId(“4c876e519e86023a30dde6b8″), “uid” : 55, “uname” : “nosqlfan55″ }

{ “_id” : ObjectId(“4c876e519e86023a30dde6b9″), “uid” : 56, “uname” : “nosqlfan56″ }

{ “_id” : ObjectId(“4c876e519e86023a30dde6ba”), “uid” : 57, “uname” : “nosqlfan57″ }

{ “_id” : ObjectId(“4c876e519e86023a30dde6bb”), “uid” : 58, “uname” : “nosqlfan58″ }

{ “_id” : ObjectId(“4c876e519e86023a30dde6bc”), “uid” : 59, “uname” : “nosqlfan59″ }

{ “_id” : ObjectId(“4c876e519e86023a30dde6bd”), “uid” : 60, “uname” : “nosqlfan60″ }

来源：http://hi.baidu.com/phpha_com/item/e2fc9c03c81d15d41ff046a4

2、mongodb与mysql相比的优缺点