翻译或纠错本页面
- Reference >
- Operators >
- Update Operators >
- Field Update Operators >
- $unset
$unset¶
- $unset¶
The $unset operator deletes a particular field. The specified value in the $unset expression (i.e. "" below) does not impact the operation. If the field does not exist, then $unset has no effect. Consider the following syntax:
{ $unset: { <field1>: "", ... } }
For example, the following update() operation uses the $unset operator to remove the fields quantity and instock from the first document found in the products collection where the field sku has a value of unknown.
db.products.update( { sku: "unknown" }, { $unset: { quantity: "", instock: "" } } )
To remove the fields from all documents in the collection where the field sku has a value of unknown, specify the multi: true option in the update() method, as in the following example:
db.products.update( { sku: "unknown" }, { $unset: { quantity: "", instock: "" } }, { multi: true } )