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How to prepend string to entire column in MongoDB?
Prepend string to entire column in MongoDB using aggregate framework. Let us first create a collection with documents −
> db.prependDemo.insertOne({"StudentFirstName":"John"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ccf3bcedceb9a92e6aa1955")
}
> db.prependDemo.insertOne({"StudentFirstName":"Chris"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ccf3bd3dceb9a92e6aa1956")
}
> db.prependDemo.insertOne({"StudentFirstName":"Robert"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ccf3bd8dceb9a92e6aa1957")
}Following is the query to display all documents from a collection with the help of find() method −
> db.prependDemo.find().pretty();
This will produce the following output −
{ "_id" : ObjectId("5ccf3bcedceb9a92e6aa1955"), "StudentFirstName" : "John" }
{
"_id" : ObjectId("5ccf3bd3dceb9a92e6aa1956"),
"StudentFirstName" : "Chris"
}
{
"_id" : ObjectId("5ccf3bd8dceb9a92e6aa1957"),
"StudentFirstName" : "Robert"
}Here is the query to prepend string to entire column in MongoDB −
> db.prependDemo.aggregate([{
... $project: {
... "StudentFirstName": {
... $concat: ["Mr.", "$StudentFirstName"]
... }
... }
... }]);This will produce the following output −
{ "_id" : ObjectId("5ccf3bcedceb9a92e6aa1955"), "StudentFirstName" : "Mr.John" }
{ "_id" : ObjectId("5ccf3bd3dceb9a92e6aa1956"), "StudentFirstName" : "Mr.Chris" }
{ "_id" : ObjectId("5ccf3bd8dceb9a92e6aa1957"), "StudentFirstName" : "Mr.Robert" }
Updated on: 30-Jul-2019
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