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MongoDB query to set user defined variable into query?
For user-defined variables, use var keyword in MongoDB. Let us create a collection with documents −
> db.demo327.insertOne({"FirstName":"Chris","LastName":"Brown"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e516952f8647eb59e562076")
}
> db.demo327.insertOne({"FirstName":"David","LastName":"Miller"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e51695af8647eb59e562077")
}
> db.demo327.insertOne({"FirstName":"John","LastName":"Doe"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e516962f8647eb59e562078")
}
> db.demo327.insertOne({"FirstName":"John","LastName":"Smith"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e516968f8647eb59e562079")
}Display all documents from a collection with the help of find() method −
> db.demo327.find();
This will produce the following output −
{ "_id" : ObjectId("5e516952f8647eb59e562076"), "FirstName" : "Chris", "LastName" : "Brown" }
{ "_id" : ObjectId("5e51695af8647eb59e562077"), "FirstName" : "David", "LastName" : "Miller" }
{ "_id" : ObjectId("5e516962f8647eb59e562078"), "FirstName" : "John", "LastName" : "Doe" }
{ "_id" : ObjectId("5e516968f8647eb59e562079"), "FirstName" : "John", "LastName" : "Smith" }Following is how to set a user-defined variable into the query −
> var name="John";
> db.demo327.find({"FirstName":name});This will produce the following output −
{ "_id" : ObjectId("5e516962f8647eb59e562078"), "FirstName" : "John", "LastName" : "Doe" }
{ "_id" : ObjectId("5e516968f8647eb59e562079"), "FirstName" : "John", "LastName" : "Smith" }
Updated on: 02-Apr-2020
335 Views
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