$lt

Syntax: {field: {$lt: value} }

$lt selects the documents where the value of the field is less than (i.e. <) the specified value.

For most data types, comparison operators only perform comparisons on fields where the BSON type matches the query value's type. MongoDB supports limited cross-BSON comparison through Type Bracketing.

Consider the following example:

db.inventory.find( { qty: { $lt: 20 } } )

This query will select all documents in the inventory collection where the qty field value is less than 20.

Consider the following example which uses the $lt operator with a field from an embedded document:

db.inventory.update( { "carrier.fee": { $lt: 20 } }, { $set: { price: 9.99 } } )

This update() operation will set the price field value in the documents that contain the embedded document carrier whose fee field value is less than 20.