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/Oracle | MongoDB | |
|---|---|---|
| Database Server | mysqld/oracle | |
| Database Client | mysql/sqlplus | mongo |
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 |
|---|---|
| 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. |
In MongoDB, the primary key is automatically set to the _idfield. |
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")
|
|
ALTER TABLE users ADD 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 users DROP 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_asc ON users(user_id) |
db.users.ensureIndex( { user_id: 1 } )
|
|
CREATE INDEX idx_user_id_asc_age_desc ON users(user_id, age DESC) |
db.users.ensureIndex( { user_id: 1, age: -1 } )
|
|
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 $and for 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 } } ) |
See find(), $gt, and $lte for more information. |
SELECT * FROM users WHERE user_id like "%bc%" |
db.users.find( { user_id: /bc/ } ) |
See find() and $regex for more information. |
SELECT * FROM users WHERE user_id like "bc%" |
db.users.find( { user_id: /^bc/ } ) |
See find() and $regex for 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() and count() for more information. |
SELECT COUNT(user_id) FROM users |
db.users.count( { user_id: { $exists: true } } )
or db.users.find( { user_id:
|