remove
Description
returns the number of documents removed from a collection using the MongoDB® C++ interface connection. Use a MongoDB query to specify removing one or multiple documents.n
= remove(conn
,collection
,mongoquery
)
Examples
Remove Documents Using MongoDB Query
Connect to MongoDB® using the MongoDB C++ interface and remove documents from a collection. Specify a MongoDB query to determine which documents to remove. In this example, the collection represents employee data.
Create a MongoDB connection to the database mongotest
using the MongoDB C++ interface. Here, the database server dbtb01
hosts this database using port number 27017
.
server = "dbtb01"; port = 27017; dbname = "mongotest"; conn = mongoc(server,port,dbname)
conn = connection with properties:
Database: "mongotest"
UserName: ""
Server: "dbtb01"
Port: 27017
CollectionNames: [14×1 string]
conn
is the connection
object that contains the MongoDB connection. The object properties contain information about the connection and the database.
The database name is
mongotest
.The user name is blank.
The database server is
dbtb01
.The port number is
27017
.This database contains 14 document collections.
Verify the MongoDB connection.
isopen(conn)
ans = logical
1
The database connection is successful because the isopen
function returns 1. Otherwise, the database connection is closed.
Create a MongoDB query to identify documents to remove. For this example, specify the employeedata
collection. Create the MongoDB query to identify documents in the department that has the department identifier set to 80
.
collection = "employeedata"; mongoquery = "{""department_id"":80}";
Remove documents using the MongoDB query. The remove
function removes three documents from the collection.
n = remove(conn,collection,mongoquery)
n = int64
3
Close the MongoDB connection.
close(conn)
Remove All Documents from Collection
Connect to MongoDB® using the MongoDB C++ interface and remove all documents from a collection. In this example, the collection represents employee data.
Create a MongoDB connection to the database mongotest
using the MongoDB C++ interface. Here, the database server dbtb01
hosts this database using port number 27017
.
server = "dbtb01"; port = 27017; dbname = "mongotest"; conn = mongoc(server,port,dbname)
conn = connection with properties:
Database: "mongotest"
UserName: ""
Server: "dbtb01"
Port: 27017
CollectionNames: [14×1 string]
conn
is the connection
object that contains the MongoDB connection. The object properties contain information about the connection and the database.
The database name is
mongotest
.The user name is blank.
The database server is
dbtb01
.The port number is
27017
.This database contains 14 document collections.
Verify the MongoDB connection.
isopen(conn)
ans = logical
1
The database connection is successful because the isopen
function returns 1. Otherwise, the database connection is closed.
Remove all documents from the employeedata
collection. Use an empty MongoDB query to specify removing all documents. The remove
function removes three documents from the collection.
collection = "employeedata"; n = remove(conn,collection,"{}")
n = int64
3
Close the MongoDB connection.
close(conn)
Input Arguments
conn
— MongoDB C++ interface connection
connection
object
MongoDB C++ interface connection, specified as a connection
object.
collection
— Collection name
string scalar
Collection name, specified as a string scalar.
Example: "taxidata"
Data Types: string
mongoquery
— MongoDB query
string scalar | character vector
MongoDB query, specified as a string scalar or character vector. Specify a JSON-style string to query the database.
Example: "{""department"":""Sales""}"
queries the database for documents
where the department
field is equal to
Sales
.
Example: "{""salary"": {""$gt"": 90000}}"
queries the database for documents
where the value of the salary
field is
greater than 90000
.
Data Types: string
| char
Output Arguments
n
— Number of documents removed
numeric scalar
Number of documents removed from a collection in the database, returned as a numeric scalar.
Version History
Introduced in R2021b
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