发布于 2015-09-14 14:58:26 | 160 次阅读 | 评论: 0 | 来源: 网络整理
Syntax: {field: {$lt: value} }
$lt selects the documents where the value of the field is less than (i.e. <) the specified value.
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.