MongoDB—SQL到MongoDB映射图表

一、术语和概念

下表显示了各种 SQL 术语和概念 以及相应的 MongoDB 术语和概念。

SQL Terms/Concepts

MongoDB Terms/Concepts

database

database

table

collection

row

document or BSON document

column

field

index

index

table joins

$lookup, embedded documents

primary key

Specify any unique column or column combination as primary key.

primary key

In MongoDB, the primary key is automatically set to the _id field.

aggregation (e.g. group by)

aggregation pipeline

See the SQL to Aggregation Mapping Chart.

SELECT INTO NEW_TABLE

$out

See the SQL to Aggregation Mapping Chart.

MERGE INTO TABLE

$merge (Available starting in MongoDB 4.2)

See the SQL to Aggregation Mapping Chart.

UNION ALL

$unionWith (Available starting in MongoDB 4.4)

transactions

transactions

二、可执行程序

下表显示了一些数据库可执行文件和相应的MongoDB可执行文件。本表并非详尽无遗。

三、示例

下表显示了各种SQL语句和相应的MongoDB语句。表中的示例假设以下条件：

• SQL示例假设一个名为people的表。
• MongoDB示例假设一个名为people的集合包含以下原型的文档：

{
  _id: ObjectId("509a8fb2f3f4948bd2f983a0"),
  user_id: "abc123",
  age: 55,
  status: 'A'
}

1、Create and Alter

下表显示了与表级操作相关的各种SQL语句以及相应的MongoDB语句。

SQL Schema Statements

MongoDB Schema Statements

CREATE TABLE people (

id MEDIUMINT NOT NULL

AUTO_INCREMENT,

user_id Varchar(30),

age Number,

status char(1),

PRIMARY KEY (id)

)

​
在第一个insertOne（）或insertMany（）操作上隐式创建。如果未指定_id字段，则自动添加主键_id。
​

db.people.insertOne( {

user_id: "abc123",

age: 55,

status: "A"

} )

然而，您也可以显式创建集合：

db.createCollection("people")

ALTER TABLE people

ADD join_date DATETIME

​托收不描述或强制执行其文件的结构；即，在收集级别没有结构变化。
然而，在文档级别，updateMany（）操作可以使用$set操作符将字段添加到现有文档中。

db.people.updateMany(

{ },

{ $set: { join_date: new Date() } }

)

ALTER TABLE people

DROP COLUMN join_date

​托收不描述或强制执行其文件的结构；即，在收集级别没有结构变化。
然而，在文档级别，updateMany（）操作可以使用$unset操作符从文档中删除字段。​

db.people.updateMany(

{ },

{ $unset: { "join_date": "" } }

)

CREATE INDEX idx_user_id_asc

ON people(user_id)

db.people.createIndex( { user_id: 1 } )

CREATE INDEX

idx_user_id_asc_age_desc

ON people(user_id, age DESC)

db.people.createIndex( { user_id: 1, age: -1 } )

DROP TABLE people

db.people.drop()

2、Insert

下表显示了与将记录插入表中相关的各种SQL语句以及相应的MongoDB语句。

SQL INSERT Statements

MongoDB insertOne() Statements

INSERT INTO people(user_id,

age,

status)

VALUES ("bcd001",

45,

"A")

db.people.insertOne(

{ user_id: "bcd001", age: 45, status: "A" }

)

3、select

下表显示了与从表中读取记录相关的各种SQL语句以及相应的MongoDB语句。

SQL SELECT Statements

MongoDB find() Statements

SELECT *

FROM people

db.people.find()

SELECT id,

user_id,

status

FROM people

db.people.find(

{ },

{ user_id: 1, status: 1 }

)

SELECT user_id, status

FROM people

db.people.find(

{ },

{ user_id: 1, status: 1, _id: 0 }

)

SELECT *

FROM people

WHERE status = "A"

db.people.find(

{ status: "A" }

)

SELECT user_id, status

FROM people

WHERE status = "A"

db.people.find(

{ status: "A" },

{ user_id: 1, status: 1, _id: 0 }

)

SELECT *

FROM people

WHERE status != "A"

db.people.find(

{ status: { $ne: "A" } }

)

SELECT *

FROM people

WHERE status = "A"

AND age = 50

db.people.find(

{ status: "A",

age: 50 }

)

SELECT *

FROM people

WHERE status = "A"

OR age = 50

db.people.find(

{ $or: [ { status: "A" } , { age: 50 } ] }

)

SELECT *

FROM people

WHERE age > 25

db.people.find(

{ age: { $gt: 25 } }

)

SELECT *

FROM people

WHERE age < 25

db.people.find(

{ age: { $lt: 25 } }

)

SELECT *

FROM people

WHERE age > 25

AND age <= 50

db.people.find(

{ age: { $gt: 25, $lte: 50 } }

)

SELECT *

FROM people

WHERE user_id like "%bc%"

db.people.find( { user_id: /bc/ } )

-or-

db.people.find( { user_id: { $regex: /bc/ } } )

SELECT *

FROM people

WHERE user_id like "bc%"

db.people.find( { user_id: /^bc/ } )

-or-

db.people.find( { user_id: { $regex: /^bc/ } } )

SELECT *

FROM people

WHERE status = "A"

ORDER BY user_id ASC

db.people.find( { status: "A" } ).sort( { user_id: 1 } )

SELECT *

FROM people

WHERE status = "A"

ORDER BY user_id DESC

db.people.find( { status: "A" } ).sort( { user_id: -1 } )

SELECT COUNT(*)

FROM people

db.people.count()

or

db.people.find().count()

SELECT COUNT(user_id)

FROM people

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

or

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

SELECT COUNT(*)

FROM people

WHERE age > 30

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

or

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

SELECT DISTINCT(status)

FROM people

db.people.aggregate( [ { $group : { _id : "$status" } } ] )

​或者，对于不超过BSON大小限制的不同值集

db.people.distinct( "status" )

SELECT *

FROM people

LIMIT 1

db.people.findOne()

or

db.people.find().limit(1)

SELECT *

FROM people

LIMIT 5

SKIP 10

db.people.find().limit(5).skip(10)

EXPLAIN SELECT *

FROM people

WHERE status = "A"

db.people.find( { status: "A" } ).explain()

4、update

下表显示了与更新表中现有记录相关的各种SQL语句以及相应的MongoDB语句。

SQL Update Statements

MongoDB updateMany() Statements

UPDATE people

SET status = "C"

WHERE age > 25

db.people.updateMany(

{ age: { $gt: 25 } },

{ $set: { status: "C" } }

)

UPDATE people

SET age = age + 3

WHERE status = "A"

db.people.updateMany(

{ status: "A" } ,

{ $inc: { age: 3 } }

)

5、delete

下表显示了与从表中删除记录相关的各种SQL语句以及相应的MongoDB语句。

SQL Delete Statements

MongoDB deleteMany() Statements

DELETE FROM people

WHERE status = "D"

db.people.deleteMany( { status: "D" } )

DELETE FROM people

db.people.deleteMany({})