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MongoDB equivalent of `select distinct(name) from collectionName where age = “25”`?
You can use distinct() to get the equivalent of select distinct. Let us first create a collection with documents −
> db.distinctNameAndAgeDemo.insertOne({"ClientFirstName":"John","Age":23});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd12759e3526dbddbbfb60b")
}
> db.distinctNameAndAgeDemo.insertOne({"ClientFirstName":"Larry","Age":25});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd12768e3526dbddbbfb60c")
}
> db.distinctNameAndAgeDemo.insertOne({"ClientFirstName":"David","Age":25});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd12773e3526dbddbbfb60d")
}
> db.distinctNameAndAgeDemo.insertOne({"ClientFirstName":"Carol","Age":26});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd1277ee3526dbddbbfb60e")
}
> db.distinctNameAndAgeDemo.insertOne({"ClientFirstName":"Sam","Age":25});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd12793e3526dbddbbfb60f")
}
> db.distinctNameAndAgeDemo.insertOne({"ClientFirstName":"Larry","Age":25});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd127a3e3526dbddbbfb610")
}
> db.distinctNameAndAgeDemo.insertOne({"ClientFirstName":"Carol","Age":26});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd127aae3526dbddbbfb611")
}Following is the query to display all documents from a collection with the help of find() method −
> db.distinctNameAndAgeDemo.find().pretty();
This will produce the following output −
{
"_id" : ObjectId("5cd12759e3526dbddbbfb60b"),
"ClientFirstName" : "John",
"Age" : 23
}
{
"_id" : ObjectId("5cd12768e3526dbddbbfb60c"),
"ClientFirstName" : "Larry",
"Age" : 25
}
{
"_id" : ObjectId("5cd12773e3526dbddbbfb60d"),
"ClientFirstName" : "David",
"Age" : 25
}
{
"_id" : ObjectId("5cd1277ee3526dbddbbfb60e"),
"ClientFirstName" : "Carol",
"Age" : 26
}
{
"_id" : ObjectId("5cd12793e3526dbddbbfb60f"),
"ClientFirstName" : "Sam",
"Age" : 25
}
{
"_id" : ObjectId("5cd127a3e3526dbddbbfb610"),
"ClientFirstName" : "Larry",
"Age" : 25
}
{
"_id" : ObjectId("5cd127aae3526dbddbbfb611"),
"ClientFirstName" : "Carol",
"Age" : 26
}Following query is the equivalent of `select distinct(name) from collectionName where age = “25” −
> db.distinctNameAndAgeDemo.distinct("ClientFirstName", {"Age": 25});This will produce the following output −
[ "Larry", "David", "Sam" ]
Above, we have displayed those client’s name whose age is 25.
Updated on: 30-Jul-2019
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