MongoDb - Query and Projection Operators

Comparison Query operators

Name Description
$gt Matches values that are greater than the value specified in the query.
$lt Matches values that are less than the value specified in the query.
$gte Matches values that are greater than or equal to the value specified in the query.
$lte Matches values that are less than or equal to the value specified in the query.
$ne Matches all values that are not equal to the value specified in the query.
$in Matches any of the values that exist in an array specified in the query.
$nin Matches values that do not exist in an array specified to the query.

Logical Query operators

Name Description
$and Joins query clauses with a logical AND returns all documents that match the conditions of both clauses.
$not Inverts the effect of a query expression and returns documents that do not match the query expression.
$or Joins query clauses with a logical OR returns all documents that match the conditions of either clause.
$nor Joins query clauses with a logical NOR returns all documents that fail to match both clauses.

Element Query operators

Name Description
$exists Matches documents that have the specified field.
$type Selects documents if a field is of the specified type.

Evaluation Query operators

Name Description
$mod Performs a modulo operation on the value of a field and selects documents with a specified result.
$regex Selects documents where values match a specified regular expression.
$where Matches documents that satisfy a JavaScript expression.

Query operator Array

Name Description
$all Matches arrays that contain all elements specified in the query.
$elemMatch Selects documents if element in the array field matches all the specified $elemMatch conditions.
$size Selects documents if the array field is a specified size.

Projection operator

Name Description
$ Projects the first element in an array that matches the query condition.
$elemMatch(projection) Projects the first element in an array that matches the specified $elemMatch condition.
$slice Limits the number of elements projected from an array. Supports skip and limit slices.

?

Source: http://www.w3resource.com/mongodb/mongodb-query-and-projection-operators.php