MongoDB regex to display records whose first five letters are uppercase?

To find MongoDB documents whose first five letters are uppercase, use the $regex operator with the pattern /^[A-Z]{5}/. The ^ ensures matching from the string beginning, and {5} specifies exactly five consecutive uppercase letters.

Syntax

db.collection.find({
    fieldName: { $regex: /^[A-Z]{5}/ }
});

Sample Data

db.upperCaseFiveLetterDemo.insertMany([
    { "StudentFullName": "JOHN Smith" },
    { "StudentFullName": "SAM Williams" },
    { "StudentFullName": "CAROL Taylor" },
    { "StudentFullName": "Bob Taylor" },
    { "StudentFullName": "DAVID Miller" }
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5cd7edef1a844af18acdffb2"),
        ObjectId("5cd7ee011a844af18acdffb3"),
        ObjectId("5cd7ee101a844af18acdffb4"),
        ObjectId("5cd7ee351a844af18acdffb5"),
        ObjectId("5cd7ee451a844af18acdffb6")
    ]
}

Display All Documents

db.upperCaseFiveLetterDemo.find().pretty();

{
    "_id": ObjectId("5cd7edef1a844af18acdffb2"),
    "StudentFullName": "JOHN Smith"
}
{
    "_id": ObjectId("5cd7ee011a844af18acdffb3"),
    "StudentFullName": "SAM Williams"
}
{
    "_id": ObjectId("5cd7ee101a844af18acdffb4"),
    "StudentFullName": "CAROL Taylor"
}
{
    "_id": ObjectId("5cd7ee351a844af18acdffb5"),
    "StudentFullName": "Bob Taylor"
}
{
    "_id": ObjectId("5cd7ee451a844af18acdffb6"),
    "StudentFullName": "DAVID Miller"
}

Count Records with First Five Uppercase Letters

db.upperCaseFiveLetterDemo.find({
    StudentFullName: { $regex: /^[A-Z]{5}/ }
}).count();

2

Display Matching Documents

db.upperCaseFiveLetterDemo.find({
    StudentFullName: { $regex: /^[A-Z]{5}/ }
});

{ "_id": ObjectId("5cd7ee101a844af18acdffb4"), "StudentFullName": "CAROL Taylor" }
{ "_id": ObjectId("5cd7ee451a844af18acdffb6"), "StudentFullName": "DAVID Miller" }

Key Points

• ^ anchor ensures matching from the beginning of the string
• [A-Z]{5} matches exactly 5 consecutive uppercase letters
• Without ^, the regex would match any 5 uppercase letters anywhere in the string

Conclusion

Use $regex: /^[A-Z]{5}/ to find documents whose field values start with exactly five uppercase letters. The caret anchor ensures precise beginning-of-string matching for accurate results.