mongodb(1)Some mongodb concept and installation on my servser
mongodb(1)Some mongodb concept and installation on my servser

1. Comparison between SQL and MongoDB
I am a new guy for mongoDB, coming from a SQL-background.
MySQL term             Mongo term/Concept
database                 database
table                      collection
index                      index
row                        BSON document
column                   BSON field
join                         embedding and linking
primary key              _id field
group by                 aggregation

BSON is a binary-encoded serialization of JSON-like documents. http://bsonspec.org/

SQL Statement                               Mongo Statement
create table users                            db.createCollection("users");
alter table users add ...

insert into users values ...                 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 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 name like "%sillycat%"    db.users.find({name:/sillycat/})

select * from users where name like "sillycat%"   db.users.find({name:/^sillycat/})

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 count() from users             db.users.count()
select count() from users where age > 30    db.users.find({age:{'$gt':30}}).count()

update users set a=1 where b='q'    db.users.update({b:'q'},{$set:{a:1}},false,true)

delete from