SQL to MongoDB

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.

Executables

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

 MySQL/OracleMongoDBDatabase Servermysqld/oraclemongodDatabase Clientmysql/sqlplusmongo

Terminology and Concepts

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

SQL Terms/ConceptsMongoDB Terms/Conceptsdatabasedatabasetablecollectionrowdocument or BSON documentcolumnfieldindexindextable joinsembedded 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 framework

See the SQL to Aggregation Framework Mapping Chart.

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 StatementsMongoDB Schema StatementsReference

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() and createCollection() for more information.

ALTER TABLE usersADD join_date DATETIME

Collections do not describe or enforce the structure of the constituent documents. See the Schema Design wiki page for more information.See update() and $set for more information on changing the structure of documents in a collection.

ALTER TABLE usersDROP COLUMN join_date

Collections do not describe or enforce the structure of the constituent documents. See the Schema Design wiki page for more information.See update() and $set for more information on changing the structure of documents in a collection.

CREATE INDEX idx_user_id_ascON users(user_id)

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

See ensureIndex() and indexes for more information.

CREATE INDEX       idx_user_id_asc_age_descON users(user_id, age DESC)

db.users.ensureIndex( { user_id: 1, age: -1 } )

See ensureIndex() and indexes 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 StatementsMongoDB insert() StatementsReference

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 StatementsMongoDB find() StatementsReference

SELECT *FROM users

db.users.find()

See find() for more information.

SELECT id, user_id, statusFROM users

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

See find() for more information.

SELECT user_id, statusFROM users

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

See find() for more information.

SELECT *FROM usersWHERE status = "A"

db.users.find(    { status: "A" })

See find() for more information.

SELECT user_id, statusFROM usersWHERE status = "A"

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

See find() for more information.

SELECT *FROM usersWHERE status != "A"

db.users.find(    { status: { $ne: "A" } })

See find() and $ne for more information.

SELECT *FROM usersWHERE status = "A"AND age = 50

db.users.find(    { status: "A",      age: 50 })

See find() and $and for more information.

SELECT *FROM usersWHERE status = "A"OR age = 50

db.users.find(    { $or: [ { status: "A" } ,             { age: 50 } ] })

See find() and $or for more information.

SELECT *FROM usersWHERE age > 25

db.users.find(    { age: { $gt: 25 } })

See find() and $gt for more information.

SELECT *FROM usersWHERE age < 25

db.users.find(   { age: { $lt: 25 } })

See find() and $lt for more information.

SELECT *FROM usersWHERE age > 25AND   age <= 50

db.users.find(   { age: { $gt: 25, $lte: 50 } })

See find(), $gt, and $lte for more information.

SELECT *FROM usersWHERE user_id like "%bc%"

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

See find() and $regex for more information.

SELECT *FROM usersWHERE user_id like "bc%"

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

See find() and $regex for more information.

SELECT *FROM usersWHERE 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 usersWHERE 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() and count() 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()

See find(), count(), and $exists for more information.

SELECT COUNT(*)FROM usersWHERE age > 30

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

or

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

See find(), count(), and $gt for more information.

SELECT DISTINCT(status)FROM users

db.users.distinct( "status" )

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

SELECT *FROM usersLIMIT 1

db.users.findOne()

or

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

See find(), findOne(), and limit() for more information.

SELECT *FROM usersLIMIT 5SKIP 10

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

See find(), limit(), and skip() for more information.

EXPLAIN SELECT *FROM usersWHERE status = "A"

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

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

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 update() StatementsReference

UPDATE usersSET status = "C"WHERE age > 25

db.users.update(   { age: { $gt: 25 } },   { $set: { status: "C" } },   { multi: true })

See update(), $gt, and $set for more information.

UPDATE usersSET age = age + 3WHERE status = "A"

db.users.update(   { status: "A" } ,   { $inc: { age: 3 } },   { multi: true })

See update(), $inc, and $set for more information.

Delete Records

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

SQL Delete StatementsMongoDB remove() StatementsReference

DELETE FROM usersWHERE status = "D"

db.users.remove( { status: "D" } )

See remove() for more information.

DELETE FROM users

db.users.remove( )

See remove() for more information.