In MongoDB, you can use the $unset field update operator to completely remove a field from a document.
The $unset operator is designed specifically to delete a field and its value from the document.
Category: DBMS
Database Management Systems
MongoDB $currentDate
In MongoDB, the $currentDate operator sets the value of a field to the current date.
It can be set as either a Date or a timestamp type. The default is Date.
$currentDate is an update operator, and can only be used when updating documents, not when inserting them (although it can be used in upsert operations).
MongoDB $toDate
In MongoDB, the $toDate aggregation operator converts a value to a date
$toDate takes any valid expression. If the expression can’t be converted to a date, it returns an error. If the expression is null or missing, it returns null.
How the $set Update Operator Works in MongoDB
The MongoDB $set update operator replaces the value of a field with the specified value.
It’s used in conjunction with update operations, for example when using the update() method to update a document.
MongoDB $mul
MongoDB has a $mul field update operator that allows you to multiply a value by a specific amount.
If the field doesn’t already exist, it is created and its value is set to zero (0) using the same numeric type as the multiplier.
MongoDB $inc
MongoDB has an $inc field update operator that allows you to increment a value by a specific amount.
You can use positive and negative values (i.e. to increment or decrement the value).
If the field doesn’t already exist, it is created with the specified value.
Continue readingMongoDB $setOnInsert
The MongoDB $setOnInsert field update operator can be used to insert a specific value during an upsert.
If an update operation results in a new document being inserted (i.e. an upsert), then the $setOnInsert operator takes effect, otherwise it has no effect.
MongoDB $max
MongoDB has a $max operator that allows you to update the value of a field only if the specified value is greater than the current value of the field.
In other words, if the $max value is greater than the current value in the document, the $max value is used. Otherwise, the document’s value remains unchanged.
MongoDB $min
MongoDB has a $min operator that allows you to update the value of a field only if the specified value is less than the current value of the field.
In other words, if the $min value is less than the current value in the document, the $min value is used. Otherwise, the document’s value remains unchanged.
MongoDB $pop
In MongoDB, you can use the $pop operator to remove the first or last element from an array.
Use $pop in conjunction with a method such as update() to update the specified document with the change.
Use -1 to remove the first element, and 1 to remove the last.