mongodb(基础用法)

驱动和客户端库

https://mongodb-documentation.readthedocs.org/en/latest/ecosystem/drivers.html#id2

https://mongodb-documentation.readthedocs.org/en/latest/ecosystem/drivers/cpp-to-sql-to-mongo-shell.html

 

窗体顶端

 

 

 

  

窗体底端

 

 

SQL to mongo Shell to C++

MongoDB queries are expressed as JSON (BSON) objects. This quick reference chart shows examples as SQL, mongo shell syntax, and MongoDB C++ driver syntax.

A query expression in MongoDB (and other things, such as an index key pattern) is represented as BSON. In C++ you can use BSONObjBuilder (aka bson::bob) to build BSON objects, or the BSON() macro. The examples below assume a connection c already established:

using namespace bson;

DBClientConnection c;

c.connect("somehost");

Several of the C++ driver methods throw mongo::DBException, so you will want a try/catch statement as some level in your program. Also be sure to call c.getLastError() after writes to check the error code.

SQL

mongo Shell

C++ Driver

INSERT INTO USERS

VALUES( 1, 1)

db.users.insert( { a: 1, b: 1 } )

// GENOID is optional. if not done by client,

// server will add an _id

 

c.insert("mydb.users",

  BSON(GENOID<<"a"<<1<<"b"<<1));

// then:

string err = c.getLastError();

SELECT a,b FROM users

db.users.find( {},

               {a: 1, b: 1 }

             )

auto_ptr<DBClientCursor> cursor =

  c.query("mydb.users", Query(),

  0, 0, BSON("a"<<1<<"b"<<1));

SELECT * FROM users

db.users.find()

auto_ptr<DBClientCursor> cursor =

  c.query("mydb.users", Query());

SELECT *

FROM users

WHERE age=33

db.users.find( { age: 33 } )

auto_ptr<DBClientCursor> cursor =

  c.query("mydb.users", QUERY("age"<<33))

// or:

auto_ptr<DBClientCursor> cursor =

  c.query("mydb.users", BSON("age"<<33))

SELECT *

FROM users

WHERE age=33

ORDER BY name

db.users.find( { age: 33 } ).sort( { name: 1 } )

auto_ptr<DBClientCursor> cursor =

  c.query("mydb.users",

    QUERY("age"<<33).sort("name"));

SELECT *

FROM users

WHERE age>33

AND age<=40

db.users.find( { 'age': { $gt:33, $lte:40 } } )

auto_ptr<DBClientCursor> cursor =

  c.query("mydb.users",

  QUERY("age"<<GT<<33<<LTE<<40));

CREATE INDEX myindexname

ON users(name)

db.users.ensureIndex( {name: 1 } )

c.ensureIndex("mydb.users", BSON("name"<<1));

SELECT *

FROM users

LIMIT 10

SKIP 20

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

auto_ptr<DBClientCursor> cursor =

  c.query("mydb.users", Query(),

          10, 20);

SELECT * FROM users LIMIT 1

db.users.findOne()

bo obj = c.findOne("mydb.users", Query());

SELECT DISTINCT last_name

FROM users

WHERE x=1

db.users.distinct( 'last_name', {x: 1} )

// no helper for distinct yet in c++ driver,

// so send command manually

bo cmdResult;

bool ok = c.runCommand(

  "mydb",

  BSON("distinct" << "users"

                  << "key" << "last_name"

                  << "query" << BSON("x"<<1)),

  cmdResult);

list<bo> results;

cmdResult["values"].Obj().Vals(results);

SELECT COUNT(*)

FROM users

where AGE > 30

db.users.find( { age: { $gt: 30 } } ).count()

unsigned long long n =

   c.count("mydb.users", BSON("age"<<GT<<30));

UPDATE users

SET a=a+2

WHERE b='q'

db.users.update( { b: 'q' },

                 { $inc: { a:2 } },

                 false, true)

c.update("mydb.users", QUERY("b"<<"q"),

         BSON("$inc"<<BSON("a"<<2)), false, true);

// then optionally:

string err = c.getLastError();

bool ok = err.empty();

DELETE

FROM users

WHERE z="abc"

db.users.remove( { z: 'abc' } )

c.remove("mydb.users", QUERY("z"<<"abc"));

// then optionally:

string err = c.getLastError();

也可以参考

SQL to MongoDB Mapping Chart

In addition to the charts that follow, you might want to consider the Frequently Asked Questions section for a selection of common questions about MongoDB.

Terminology and Concepts

The following table presents the various SQL terminology and concepts and the corresponding MongoDB terminology and concepts.

SQL Terms/Concepts

MongoDB Terms/Concepts

database

database

table

collection

row

document or BSON document

column

field

index

index

table joins

embedded documents and linking

primary key

Specify any unique column or column combination as primary key.

primary key

In MongoDB, the primary key is automatically set to the _idfield.

aggregation (e.g. group by)

aggregation pipeline

See the SQL to Aggregation Mapping Chart.

Executables

The following table presents the MySQL/Oracle executables and the corresponding MongoDB executables.

 

MySQL/Oracle

MongoDB

Database Server

mysqld/oracle

mongod

Database Client

mysql/sqlplus

mongo

Examples

The following table presents the various SQL statements and the corresponding MongoDB statements. The examples in the table assume the following conditions:

  • The SQL examples assume a table named users.
  • The MongoDB examples assume a collection named users that contain documents of the following prototype:
·                {
·                  _id: ObjectID("509a8fb2f3f4948bd2f983a0"),
·                  user_id: "abc123",
·                  age: 55,
·                  status: 'A'
·                }

Create and Alter

The following table presents the various SQL statements related to table-level actions and the corresponding MongoDB statements.

SQL Schema Statements

MongoDB Schema Statements

Reference

 
CREATE TABLE users (
    id MEDIUMINT NOT NULL
        AUTO_INCREMENT,
    user_id Varchar(30),
    age Number,
    status char(1),
    PRIMARY KEY (id)
)

Implicitly created on first insert() operation. The primary key_id is automatically added if _id field is not specified.

db.users.insert( {
    user_id: "abc123",
    age: 55,
    status: "A"
 } )

However, you can also explicitly create a collection:

db.createCollection("users")

See insert() anddb.createCollection()for more information.

 
ALTER TABLE users
ADD join_date DATETIME

Collections do not describe or enforce the structure of its documents; i.e. there is no structural alteration at the collection level.

However, at the document level, update() operations can add fields to existing documents using the $set operator.

db.users.update(
    { },
    { $set: { join_date: new Date() } },
    { multi: true }
)

See the Data Modeling Concepts, update(), and$set for more information on changing the structure of documents in a collection.

 
ALTER TABLE users
DROP COLUMN join_date

Collections do not describe or enforce the structure of its documents; i.e. there is no structural alteration at the collection level.

However, at the document level, update() operations can remove fields from documents using the $unset operator.

db.users.update(
    { },
    { $unset: { join_date: "" } },
    { multi: true }
)

See Data Modeling Concepts, update(), and$unset for more information on changing the structure of documents in a collection.

 
CREATE INDEX idx_user_id_asc
ON users(user_id)
 
db.users.ensureIndex( { user_id: 1 } )

See ensureIndex() andindexes for more information.

 
CREATE INDEX
       idx_user_id_asc_age_desc
ON users(user_id, age DESC)
 
db.users.ensureIndex( { user_id: 1, age: -1 } )

See ensureIndex() andindexes for more information.

 
DROP TABLE users
 
db.users.drop()

See drop() for more information.

Insert

The following table presents the various SQL statements related to inserting records into tables and the corresponding MongoDB statements.

SQL INSERT Statements

MongoDB insert() Statements

Reference

 
INSERT INTO users(user_id,
                  age,
                  status)
VALUES ("bcd001",
        45,
        "A")
 
db.users.insert( {
       user_id: "bcd001",
       age: 45,
       status: "A"
} )

See insert() for more information.

Select

The following table presents the various SQL statements related to reading records from tables and the corresponding MongoDB statements.

SQL SELECT Statements

MongoDB find() Statements

Reference

 
SELECT *
FROM users
 
db.users.find()

See find()for more information.

 
SELECT id, user_id, status
FROM users
 
db.users.find(
    { },
    { user_id: 1, status: 1 }
)

See find()for more information.

 
SELECT user_id, status
FROM users
 
db.users.find(
    { },
    { user_id: 1, status: 1, _id: 0 }
)

See find()for more information.

 
SELECT *
FROM users
WHERE status = "A"
 
db.users.find(
    { status: "A" }
)

See find()for more information.

 
SELECT user_id, status
FROM users
WHERE status = "A"
 
db.users.find(
    { status: "A" },
    { user_id: 1, status: 1, _id: 0 }
)

See find()for more information.

 
SELECT *
FROM users
WHERE status != "A"
 
db.users.find(
    { status: { $ne: "A" } }
)

See find()and $ne for more information.

 
SELECT *
FROM users
WHERE status = "A"
AND age = 50
 
db.users.find(
    { status: "A",
      age: 50 }
)

See find()and $andfor more information.

 
SELECT *
FROM users
WHERE status = "A"
OR age = 50
 
db.users.find(
    { $or: [ { status: "A" } ,
             { age: 50 } ] }
)

See find()and $or for more information.

 
SELECT *
FROM users
WHERE age > 25
 
db.users.find(
    { age: { $gt: 25 } }
)

See find()and $gt for more information.

 
SELECT *
FROM users
WHERE age < 25
 
db.users.find(
   { age: { $lt: 25 } }
)

See find()and $lt for more information.

 
SELECT *
FROM users
WHERE age > 25
AND   age <= 50
 
db.users.find(
   { age: { $gt: 25, $lte: 50 } }
)

Seefind(),$gt, and$lte for more information.

 
SELECT *
FROM users
WHERE user_id like "%bc%"
 
db.users.find(
   { user_id: /bc/ }
)

See find()and $regexfor more information.

 
SELECT *
FROM users
WHERE user_id like "bc%"
 
db.users.find(
   { user_id: /^bc/ }
)

See find()and $regexfor more information.

 
SELECT *
FROM users
WHERE status = "A"
ORDER BY user_id ASC
 
db.users.find( { status: "A" } ).sort( { user_id: 1 } )

See find()and sort()for more information.

 
SELECT *
FROM users
WHERE status = "A"
ORDER BY user_id DESC
 
db.users.find( { status: "A" } ).sort( { user_id: -1 } )

See find()and sort()for more information.

 
SELECT COUNT(*)
FROM users
 
db.users.count()

or

db.users.find().count()

See find()andcount() for more information.

 
SELECT COUNT(user_id)
FROM users
 
db.users.count( { user_id: { $exists: true } } )

or

db.users.find( { user_id: { $exists: true } } ).count()

Seefind(),count(), and$exists for more information.

 
SELECT COUNT(*)
FROM users
WHERE age > 30
 
db.users.count( { age: { $gt: 30 } } )

or

db.users.find( { age: { $gt: 30 } } ).count()

Seefind(),count(), and $gt for more information.

 
SELECT DISTINCT(status)
FROM users
 
db.users.distinct( "status" )

See find()anddistinct()for more information.

 
SELECT *
FROM users
LIMIT 1
 
db.users.findOne()

or

db.users.find().limit(1)

Seefind(),findOne(), andlimit() for more information.

 
SELECT *
FROM users
LIMIT 5
SKIP 10
 
db.users.find().limit(5).skip(10)

Seefind(),limit(), and skip()for more information.

 
EXPLAIN SELECT *
FROM users
WHERE status = "A"

 

 
posted @ 2014-03-11 14:58  zzyoucan  阅读(623)  评论(0)  编辑  收藏  举报