$not returns the Boolean value to opposite of its expression,
suppose expression evaluates the value false $not evaluate it true same as if the expression evaluates true $not evaluate as false. $not operator treat as false
to null, 0 and undefined.
Syntax:
{ $not: [ <expression> ] }
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Example:
Suppose
we have a collection named "books". Write a query to select books which quantity is not
less than 3.
{ "_id" : 1, "book_title" : "book1
","price" : 20, "quantity" : 1, "date" :
ISODate("2016-08-05T07:00:00Z") }
{ "_id" : 2, "book_title" : "book2",
"price" : 10, "quantity" : 2, "date" :
ISODate("2016-08-05T08:00:00Z") }
{ "_id" : 3, "book_title" : "book3",
"price" : 30, "quantity" : 4, "date" :
ISODate("2016-08-17T10:00:00Z") }
{ "_id" : 4, "book_title" : "book4",
"price" : 10, "quantity" : 2, "date" :
ISODate("2014-09-01T11:20:39.736Z") }
{ "_id" : 5, "book_title" : "book5",
"price" : 20, "quantity" : 6, "date" :
ISODate("2014-09-04T20:23:13.331Z") }
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Query:
db.books.find({
"quantity":{$not:{"$lt":3}}
})
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Result:
{"_id" : 3,"book_title" :
"book3","price" : 30,"quantity" :
4,"date" : ISODate("2016-08-17T10:00:00.000Z")}
{"_id" : 5,"book_title" :
"book5","price" : 20,"quantity" : 6,"date"
: ISODate("2014-09-04T20:23:13.331Z")}
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