Count Method: MongoDB

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Let’s learn to use count() method in MongoDB.

Count method outputs numeric value of the number of documents retrieved.

count-method-mongodb

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> use test
switched to db test
> db.names.find().pretty()
{ "_id" : ObjectId("53be5d4604cc1cb0a7bfc3c0"), "name" : "Alia" }
{ "_id" : ObjectId("53be5d5204cc1cb0a7bfc3c1"), "name" : "Bebo" }
{ "_id" : ObjectId("53be5d5904cc1cb0a7bfc3c2"), "name" : "Chameli" }
{ "_id" : ObjectId("53be5d6104cc1cb0a7bfc3c3"), "name" : "Dev D" }
{ "_id" : ObjectId("53be5d6804cc1cb0a7bfc3c4"), "name" : "Emli" }
{ "_id" : ObjectId("53be5d8604cc1cb0a7bfc3c5"), "name" : "Farhan" }
{ "_id" : ObjectId("53be5d9204cc1cb0a7bfc3c6"), "name" : "Gangs" }
{ "_id" : ObjectId("53be5d9904cc1cb0a7bfc3c7"), "name" : "Hum" }
{ "_id" : ObjectId("53be5e3704cc1cb0a7bfc3c8"), "name" : 25 }
> db.names.count();
9
> db.names.count({"name": {$type: 2}});
8
> db.names.count({"name": {$type: 1}});
1
> db.names.count({"name": {$regex: "e"}});
3

We have 9 documents, out of which 8 documents have string values as name and 1 document has numeric value as it’s name.

Count Method: MongoDB


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Related Read: $exists, $type, $regex operators: MongoDB

$type: 2, represents string value in BSON specification. And we have 8 documents with string value for the name field.

$type: 1, represents double value in BSON specification. And we have 1 document with numeric value for the name field.

$regex: “e”, we have 3 documents which has small letter e in the string value for name field.

Note: We can make use of count() method, when we want to show the number of friends or followers each member has. So MongoDB makes it easy by facilitating developers with count() method.

SELECT / LIST Records From Database Table: PHP & MySQL
In sql, we have SELECT count(*) FROM table_name;

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