MongoDB $strcasecmp Operator

MongoDB $strcasecmp operator performs a case-insensitive comparison between two strings.

The $strcasecmp operator in MongoDB is used to compare two strings. It is a string expression operator used in the aggregation pipeline to perform case-insensitive string comparisons.

The result of this operator can be explained in three cases:

• If the first string is greater than the second string, then this operator will return 1. 
• If the first string is less than the second string, then this operator will return -1. 
• If both the strings are equal, then this operator will return 0.

{ $strcasecmp: [ <expression1>, <expression2> ] }

Here, the arguments passed in this operator can be any valid expression until they resolve to strings.

To understand it better, let’s look at some examples of the MongoDB $strcasecmp Operator.

In the following examples, we are working with:

Database: w3wiki
Collection: employee
Document: three documents that contain the details of the employees in the form of field-value pairs.

Example 1: Using $strcasecmp Operator

In this example, we are going compare the value of the department field of all the documents present in employee collection with the “development” string using $strcasecmp operator. 

Query:

db.employee.aggregate([
... {$project: {"name.first": 1, _id: 0, result:
... {$strcasecmp: ["$department", "development"]}}}])

Output:

Example 2: Using $strcasecmp Operator in the Embedded Document

In this example, we are going compare the value of the name.first field of all the documents present in employee collection with the “Sunita” string using $strcasecmp operator. 

Query:

db.employee.aggregate([
... {$project: {result: {$strcasecmp: ["$name.first", "Sunita"]}}}])

Output:

• The MongoDB $strcasecmp operator is used in the aggregation pipeline stages to perform a case-insensitive comparison of two strings.
• It returns 1 if the first string is “greater than” the second string, 0 if the two strings are equal, and -1 if the first string is “less than” the second string.
• The operator is useful for scenarios where case sensitivity is not required, and a simple string comparison is needed.
• $strcasecmp internally capitalizes strings before comparing them to provide a case-insensitive comparison.
• It may not make sense when applied to glyphs outside the Roman alphabet.