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Implementing String Comparison in MongoDB?
To implement string comparison in MongoDB, use $strcasecmp. It performs case-insensitive comparison of two strings. It returns −
1 if first string is “greater than” the second string.
0 if the two strings are equal.
-1 if the first string is “less than” the second string.
Let us create a collection with documents −
> db.demo490.insertOne({"Name1":"John","Name2":"john"});{
"acknowledged" : true,
"insertedId" : ObjectId("5e8496ccb0f3fa88e22790bb")
}
> db.demo490.insertOne({"Name1":"David","Name2":"Bob"});{
"acknowledged" : true,
"insertedId" : ObjectId("5e8496d9b0f3fa88e22790bc")
}
> db.demo490.insertOne({"Name1":"Carol","Name2":"Carol"});{
"acknowledged" : true,
"insertedId" : ObjectId("5e8496e5b0f3fa88e22790bd")
}Display all documents from a collection with the help of find() method −
> db.demo490.find();
This will produce the following output −
{ "_id" : ObjectId("5e8496ccb0f3fa88e22790bb"), "Name1" : "John", "Name2" : "john" }
{ "_id" : ObjectId("5e8496d9b0f3fa88e22790bc"), "Name1" : "David", "Name2" : "Bob" }
{ "_id" : ObjectId("5e8496e5b0f3fa88e22790bd"), "Name1" : "Carol", "Name2" : "Carol" }Following is the query to implement string comparison in MongoDB −
> db.demo490.aggregate(
... [
... {
... $project:
... {
... Name1: 1,
... Name2: 1,
... Result: { $strcasecmp: [ "$Name1", "$Name2" ] }
... }
... }
... ]
... )This will result the following output −
{ "_id" : ObjectId("5e8496ccb0f3fa88e22790bb"), "Name1" : "John", "Name2" : "john", "Result"
: 0 }
{ "_id" : ObjectId("5e8496d9b0f3fa88e22790bc"), "Name1" : "David", "Name2" : "Bob",
"Result" : 1 }
{ "_id" : ObjectId("5e8496e5b0f3fa88e22790bd"), "Name1" : "Carol", "Name2" : "Carol",
"Result" : 0 }
Updated on: 11-May-2020
516 Views
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