SQL 到 MongoDB 的映射表

在此页面上

Terminology and Concepts
Executables
示例
深入阅读

In addition to the charts that follow, you might want to consider the 常见问题解答 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	集合
row	文档 or BSON document
column	字段
索引（index）	索引（index）
table joins	`$lookup`, embedded documents
主键 Specify any unique column or column combination as primary key.	主键 In MongoDB, the primary key is automatically set to the _id field.
aggregation (e.g. group by)	聚合管道 See the SQL 聚合映射图表.
SELECT INTO NEW_TABLE	`$out` See the SQL 聚合映射图表.
MERGE INTO TABLE	`$merge` See the SQL 聚合映射图表.
UNION ALL	`$unionWith`
事务	事务 For many scenarios, the denormalized data model (embedded documents and arrays) will continue to be optimal for your data and use cases instead of multi-document transactions. That is, for many scenarios, modeling your data appropriately will minimize the need for multi-document transactions.

Executables

The following table presents some database executables and the corresponding MongoDB executables. This table is not meant to be exhaustive.

	MongoDB	MySQL	Oracle	Informix	DB2
Database Server	`mongod`	`mysqld`	`oracle`	`IDS`	`DB2 Server`
Database Client	`mongosh`	`mysql`	`sqlplus`	`DB-Access`	`DB2 Client`

示例

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 people.
The MongoDB examples assume a collection named people 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

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

Implicitly created on first insertOne() or insertMany() operation. The primary key _id is automatically added if _id field is not specified.

db.people.insertOne( {
    user_id: "abc123",
    age: 55,
    status: "A"
 } )

However, you can also explicitly create a collection:

db.createCollection("people")

ALTER TABLE people
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, updateMany() operations can add fields to existing documents using the $set operator.

db.people.updateMany(
    { },
    { $set: { join_date: new Date() } }
)

ALTER TABLE people
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, updateMany() operations can remove fields from documents using the $unset operator.

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()

For more information on the methods and operators used, see:

另请参阅：

Insert

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

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" }
)

有关更多信息，请参阅 db.collection.insertOne()。

另请参阅：

Select

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

注意

The find() method always includes the _id field in the returned documents unless specifically excluded through 投影. Some of the SQL queries below may include an _id field to reflect this, even if the field is not included in the corresponding find() query.

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/ } )

-或-

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

SELECT *
FROM people
WHERE user_id like "bc%"

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

-或-

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()

db.people.find().count()

SELECT COUNT(user_id)
FROM people

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

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

SELECT COUNT(*)
FROM people
WHERE age > 30

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

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

SELECT DISTINCT(status)
FROM people

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

or, for distinct value sets that do not exceed the BSON size limit

db.people.distinct( "status" )

SELECT *
FROM people
LIMIT 1

db.people.findOne()

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()

For more information on the methods and operators used, see

另请参阅：

Update Records

The following table presents the various SQL statements related to updating existing records in tables and the corresponding MongoDB statements.

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 } }
)

For more information on the method and operators used in the examples, see:

另请参阅：

Delete Records

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

SQL Delete Statements

MongoDB deleteMany() Statements

DELETE FROM people
WHERE status = "D"

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

DELETE FROM people

db.people.deleteMany({})

有关更多信息，请参阅 db.collection.deleteMany()。

另请参阅：

深入阅读

If you are considering migrating your SQL application to MongoDB, download the MongoDB Application Modernization Guide.

下载内容包括以下资源：

介绍使用 MongoDB 进行数据建模的方法
白皮书介绍了从 RDBMS 数据模型迁移到 MongoDB 的最佳实践和注意事项
引用 MongoDB 模式及其 RDBMS 等效模式
应用程序现代化记分卡

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