MongoDB于SQL的对应

 

首先介绍一些关系数据库中常用的概念对比MongoDB中与之对应的概念。

 

                                      Oracle                                                                                                          MongoDB

                                     DataBase                                                                                                      DataBase

                                     Table(表)                                                                                                       Collection(集合)

                                    index(索引)                                                                                                      index(索引)

                                     row(一行记录)                                                                                  BSON(类似JSON格式) http://bsonspec.org/

                                      column(列,字段)                                                                                          BSON中的字段

                                      join(连接)                                                                                  embedding and linking(嵌入和连接)

                                     primary key(主键)                                                                                       _id field(ID标识符)

                                      group by(分组)                                                                                        aggregation(聚合)

                                      其实在学习MongoDB过程中我们就是要忘记模式,记住”键值对”就可以啦。

                       MongoDB的查询是通过JSON(BSON)对象，来表示的。接下来我们将通过对比展示SQL和MonggoDB的查询语法

 

                                                                SQL语句                                                                                             MongoDB语句

                Create table users(a int,b int)建立一张表                     我们无需显式创建Collection,前面讲了在我们保存第一条文档的时候MongoDB会自动创建，当然我们也可以显示的建立：
                                                                            Collection: db.createCollection("users", { capped:true, size:100000}) // capped:是否覆盖 size:大小以字节为单位

 

                             Alter table users………                                                                                                                 模式自由

 

inert into users value(3,5)	db.users.insert({a:3,b:5})
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:{$gt:33}})
select * from users where age!=33	db.users.find({age:{$ne: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})
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( { $or : [ { a : 1 } , { b : 2 } ] } )
select * from users limit 1	db.users.findOne()
select order_id from orders o, order_line_items li where li.order_id=o.order_id and li.sku=12345	db.orders.find({"items.sku":12345},{_id:1})
select customer.name from customers,orders where orders.id="q179" and orders.custid=customer.id	var o = db.orders.findOne({_id:"q179"}); var name = db.customers.findOne({_id:o.custid})
select distinct last_name from users	db.users.distinct('last_name')
select count(*y) from users	db.users.count()
select count(*y) from users where age > 30	db.users.find({age: {'$gt': 30}}).count()
select count(age) from users	db.users.find({age: {'$exists': true}}).count()
create index myindexname on users(name)	db.users.ensureIndex({name:1})
create index myindexname ON users(name,ts desc)	db.users.ensureIndex({name:1,ts:-1})
explain select * from users where z=3	db.users.find({z:3}).explain()
update users set a=1 where b='q'	db.users.update({b:'q'}, {$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'});

 

更多请见: http://api.mongodb.org/wiki/current/SQL%20to%20Aggregation%20Framework%20Mapping%20Chart.html

这些都是常用的SQL语句，当然掌握这些就足够后面的开发啦。

 

SQL Statement Mongo Query Language Statement

CREATE TABLE USERS (a Number, b Number)	Implicit or use MongoDB::createCollection().
INSERT INTO USERS VALUES(1,1)	$db->users->insert(array("a" => 1, "b" => 1));
SELECT a,b FROM users	$db->users->find(array(), array("a" => 1, "b" => 1));
SELECT * FROM users WHERE age=33	$db->users->find(array("age" => 33));
SELECT a,b FROM users WHERE age=33	$db->users->find(array("age" => 33), array("a" => 1, "b" => 1));
SELECT a,b FROM users WHERE age=33 ORDER BY name	$db->users->find(array("age" => 33), array("a" => 1, "b" => 1))->sort(array("name" => 1));
SELECT * FROM users WHERE age>33	$db->users->find(array("age" => array('$gt' => 33)));
SELECT * FROM users WHERE age<33	$db->users->find(array("age" => array('$lt' => 33)));
SELECT * FROM users WHERE name LIKE "%Joe%"	$db->users->find(array("name" => new MongoRegex("/Joe/")));
SELECT * FROM users WHERE name LIKE "Joe%"	$db->users->find(array("name" => new MongoRegex("/^Joe/")));
SELECT * FROM users WHERE age>33 AND age<=40	$db->users->find(array("age" => array('$gt' => 33, '$lte' => 40)));
SELECT * FROM users ORDER BY name DESC	$db->users->find()->sort(array("name" => -1));
CREATE INDEX myindexname ON users(name)	$db->users->ensureIndex(array("name" => 1));
CREATE INDEX myindexname ON users(name,ts DESC)	$db->users->ensureIndex(array("name" => 1, "ts" => -1));
SELECT * FROM users WHERE a=1 and b='q'	$db->users->find(array("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	$db->users->find(array('$or' => array(array("a" => 1), array("b" => 2))));
SELECT * FROM users LIMIT 1	$db->users->find()->limit(1);
EXPLAIN SELECT * FROM users WHERE z=3	$db->users->find(array("z" => 3))->explain()
SELECT DISTINCT last_name FROM users	$db->command(array("distinct" => "users", "key" => "last_name"));
SELECT COUNT(*y) FROM users	$db->users->count();
SELECT COUNT(*y) FROM users where AGE > 30	$db->users->find(array("age" => array('$gt' => 30)))->count();
SELECT COUNT(AGE) from users	$db->users->find(array("age" => array('$exists' => true)))->count();
UPDATE users SET a=1 WHERE b='q'	$db->users->update(array("b" => "q"), array('$set' => array("a" => 1)));
UPDATE users SET a=a+2 WHERE b='q'	$db->users->update(array("b" => "q"), array('$inc' => array("a" => 2)));
DELETE FROM users WHERE z="abc"	$db->users->remove(array("z" => "abc"));