Update Operators
Fields
Name | Description |
$currentDate | Sets the value of a field to current date, either as a Date or a Timestamp. |
$inc | Increments the value of the field by the specified amount. |
$min | Only updates the field if the specified value is less than the existing field value. |
$max | Only updates the field if the specified value is greater than the existing field value. |
$mul | Multiplies the value of the field by the specified amount. |
$rename | Renames a field. |
$set | Sets the value of a field in a document. |
$setOnInsert | Sets the value of a field if an update results in an insert of a document. Has no effect on update operations that modify existing documents. |
$unset | Removes the specified field from a document. |
Array
Operators
Name | Description |
$ | Acts as a placeholder to update the first element that matches the query condition. |
$[] | Acts as a placeholder to update all elements in an array for the documents that match the query condition. |
$[<identifier>] | Acts as a placeholder to update all elements that match the |
$addToSet | Adds elements to an array only if they do not already exist in the set. |
$pop | Removes the first or last item of an array. |
$pull | Removes all array elements that match a specified query. |
$push | Adds an item to an array. |
$pullAll | Removes all matching values from an array. |
Modifiers
Name | Description |
$each | Modifies the $push and $addToSet operators to append multiple items for array updates. |
$position | Modifies the $push operator to specify the position in the array to add elements. |
$slice | Modifies the $push operator to limit the size of updated arrays. |
$sort | Modifies the $push operator to reorder documents stored in an array. |
Bitwise
Name | Description |
$bit | Performs bitwise |
参考：https://docs.mongodb.com/manual/reference/operator/update/
