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  • 21.SQL to MongoDB Mapping Chart-官方文档摘录

    有关关系型数据库跟Mongod的语法对比

    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/ConceptsMongoDB 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 _idfield.
    aggregation (e.g. group by)

    aggregation pipeline

    See the SQL to Aggregation Mapping Chart.

    Executables

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

     MongoDBMySQLOracleInformixDB2
    Database Server mongod mysqld oracle IDS DB2 Server
    Database Client mongo mysql sqlplus DB-Access DB2 Client

    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 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 StatementsMongoDB 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, see:

    Insert

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

    SQL INSERT StatementsMongoDB insertOne() Statements
     
    INSERT INTO people(user_id,
                  age,
                  status)
VALUES ("bcd001",
        45,
        "A")

    db.people.insertOne(
   { user_id: "bcd001", age: 45, status: "A" }
)

    For more information, see db.collection.insertOne().

    Select

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

    NOTE

    The find() method always includes the _id field in the returned documents unless specifically excluded through projection. 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 StatementsMongoDB 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.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()

    For more information, see:

    Update Records

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

    SQL Update StatementsMongoDB 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, see db.collection.updateMany(), $set, $inc, and $gt.

    Delete Records

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

    SQL Delete StatementsMongoDB deleteMany() Statements
     
    DELETE FROM people
WHERE status = "D"

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

    DELETE FROM people

    db.people.deleteMany({})

    For more information, see db.collection.deleteMany().
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  • 原文地址：https://www.cnblogs.com/olinux/p/7358607.html
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