$nor¶
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$nor¶ $norperforms a logicalNORoperation on an array of one or more query expression and selects the documents that fail all the query expressions in the array. The$norhas the following syntax:{ $nor: [ { <expression1> }, { <expression2> }, ... { <expressionN> } ] }
Examples¶
$nor Query with Two Expressions¶
Consider the following query which uses only the $nor operator:
db.inventory.find( { $nor: [ { price: 1.99 }, { sale: true } ] } )
This query will return all documents that:
- contain the
pricefield whose value is not equal to1.99and contain thesalefield whose value is not equal totrueor - contain the
pricefield whose value is not equal to1.99but do not contain thesalefield or - do not contain the
pricefield but contain thesalefield whose value is not equal totrueor - do not contain the
pricefield and do not contain thesalefield
$nor and Additional Comparisons¶
Consider the following query:
db.inventory.find( { $nor: [ { price: 1.99 }, { qty: { $lt: 20 } }, { sale: true } ] } )
This query will select all documents in the inventory collection
where:
- the
pricefield value does not equal1.99and - the
qtyfield value is not less than20and - the
salefield value is not equal totrue
including those documents that do not contain these field(s).
The exception in returning documents that do not contain the field
in the $nor expression is when the $nor operator is
used with the $exists operator.
$nor and $exists¶
Compare that with the following query which uses the
$nor operator with the $exists operator:
db.inventory.find( { $nor: [ { price: 1.99 }, { price: { $exists: false } },
{ sale: true }, { sale: { $exists: false } } ] } )
This query will return all documents that:
- contain the
pricefield whose value is not equal to1.99and contain thesalefield whose value is not equal totrue