true }} ) // find users matching a regular expression > db.users.find( {username: /^ro*/i } ) // count posts by author > db.users.find( {username: "Ross"} ).count() Query Operators Conditional Operators – $all, $exists, $mod, $ne, $in, $nin, $nor, $or, $size, $type – $lt, $lte, $gt, $gte"