$or operator returns the value of one expression true from
it’s all expression. Its takes any number of expression. $or operator same as like
OR operator in SQL Server.
$or operator stops the evaluation if it finds expression true
for it’s all expression. $or operator treat as true to null, 0 and undefined.
Syntax:
{ $or: [ <expression1>, <expression2>, ... ] }
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Example:
Suppose
we have a collection book. Write a query to select books in which quantity =1 or price
is 20.
{ "_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({
$or:[{"quantity":1},{"price":20}]
})
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Result:
{ "_id" : 1, "book_title" : "book1 ",
"price" : 20, "quantity" : 1, "date" :
ISODate("2016-08-05T07:00:00.000Z") }
{ "_id" : 5, "book_title" : "book5",
"price" : 20, "quantity" : 6, "date" :
ISODate("2014-09-04T20:23:13.331Z") }
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