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$and (aggregation)![](/docs/v5.3/assets/link.svg)
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Definition![](/docs/v5.3/assets/link.svg)
$and
Evaluates one or more expressions and returns
true
if all of the expressions aretrue
or if run with no argument expressions. Otherwise,$and
returnsfalse
.$and
syntax:{ $and: [ <expression1>, <expression2>, ... ] } For more information on expressions, see Expressions.
Behavior![](/docs/v5.3/assets/link.svg)
In addition to the false
boolean value, $and
evaluates
as false
the following: null
, 0
, and undefined
values. The $and
evaluates all other values as true
,
including non-zero numeric values and arrays.
Example | Result |
---|---|
{ $and: [ 1, "green" ] } | true |
{ $and: [ ] } | true |
{ $and: [ [ null ], [ false ], [ 0 ] ] } | true |
{ $and: [ null, true ] } | false |
{ $and: [ 0, true ] } | false |
Error Handling![](/docs/v5.3/assets/link.svg)
To allow the query engine to optimize queries, $and
handles
errors as follows:
If any expression supplied to
$and
would cause an error when evaluated alone, the$and
containing the expression may cause an error but an error is not guaranteed.An expression supplied after the first expression supplied to
$and
may cause an error even if the first expression evaluates tofalse
.
For example, the following query always produces an error if $x
is
0
:
db.example.find( { $expr: { $eq: [ { $divide: [ 1, "$x" ] }, 3 ] } } )
The following query, which contains multiple expressions supplied to
$and
, may produce an error if there is any document where $x
is 0
:
db.example.find( { $and: [ { x: { $ne: 0 } }, { $expr: { $eq: [ { $divide: [ 1, "$x" ] }, 3 ] } } ] } )
Example![](/docs/v5.3/assets/link.svg)
Create an example inventory
collection with these documents:
db.inventory.insertMany([ { "_id" : 1, "item" : "abc1", description: "product 1", qty: 300 }, { "_id" : 2, "item" : "abc2", description: "product 2", qty: 200 }, { "_id" : 3, "item" : "xyz1", description: "product 3", qty: 250 }, { "_id" : 4, "item" : "VWZ1", description: "product 4", qty: 300 }, { "_id" : 5, "item" : "VWZ2", description: "product 5", qty: 180 } ])
This operation uses the $and
operator to
determine if qty
is greater than 100 and less than 250
:
db.inventory.aggregate( [ { $project: { item: 1, qty: 1, result: { $and: [ { $gt: [ "$qty", 100 ] }, { $lt: [ "$qty", 250 ] } ] } } } ] )
The operation returns these results:
{ "_id" : 1, "item" : "abc1", "qty" : 300, "result" : false } { "_id" : 2, "item" : "abc2", "qty" : 200, "result" : true } { "_id" : 3, "item" : "xyz1", "qty" : 250, "result" : false } { "_id" : 4, "item" : "VWZ1", "qty" : 300, "result" : false } { "_id" : 5, "item" : "VWZ2", "qty" : 180, "result" : true }