How to get the count of Notes/Documents

Hello API team,

I am looking to get a count of notes/documents imported into a database.

{
    "Note": {
        "Scope": {
            "Fields": {
                "$COUNT(key)": 1
            }
        },
        "Criteria": {
            "SearchQuery": {
                "ParentKey": {
                    "$EQ": "User Identification"
                }
            }
        }
    }
}

Here is what I have but they are returning Null. Rasto mentioned SQL drivers should be used but I am sure if there is one for Notes/Documents.

Thank you,