在 MongoDB 中的结构元素上检查 $gt [重复]答案

【问题标题】：Checking $gt on a structure element in MongoDB [duplicate]在 MongoDB 中的结构元素上检查 $gt [重复]
【发布时间】：2020-09-11 00:13:10
【问题描述】：

> db.inventory.find()
{ "_id" : ObjectId("5eb67598bee5213484d45087"), "item" : "journal", "qty" : 25, "status" : "A", "size" : { "h" : 14, "w" : 21, "uom" : "cm" }, "tags" : [ "blank", "red" ] }
{ "_id" : ObjectId("5eb67598bee5213484d45088"), "item" : "notebook", "qty" : 50, "status" : "A", "size" : { "h" : 8.5, "w" : 11, "uom" : "in" }, "tags" : [ "red", "blank" ] }
{ "_id" : ObjectId("5eb67598bee5213484d45089"), "item" : "paper", "qty" : 10, "status" : "D", "size" : { "h" : 8.5, "w" : 11, "uom" : "in" }, "tags" : [ "red", "blank", "plain" ] }
{ "_id" : ObjectId("5eb67598bee5213484d4508a"), "item" : "planner", "qty" : 0, "status" : "D", "size" : { "h" : 22.85, "w" : 30, "uom" : "cm" }, "tags" : [ "blank", "red" ] }
{ "_id" : ObjectId("5eb67598bee5213484d4508b"), "item" : "postcard", "qty" : 45, "status" : "A", "size" : { "h" : 10, "w" : 15.25, "uom" : "cm" }, "tags" : [ "blue" ] }
{ "_id" : ObjectId("5ebfd02b3a3b38a52be04608"), "item" : "journal", "qty" : 25, "tags" : [ "blank", "red" ], "dim_cm" : [ 14, 21 ] }
{ "_id" : ObjectId("5ebfd02b3a3b38a52be04609"), "item" : "notebook", "qty" : 50, "tags" : [ "red", "blank" ], "dim_cm" : [ 14, 21 ] }
{ "_id" : ObjectId("5ebfd02b3a3b38a52be0460a"), "item" : "paper", "qty" : 100, "tags" : [ "red", "blank", "plain" ], "dim_cm" : [ 14, 21 ] }
{ "_id" : ObjectId("5ebfd02b3a3b38a52be0460b"), "item" : "planner", "qty" : 75, "tags" : [ "blank", "red" ], "dim_cm" : [ 22.85, 30 ] }
{ "_id" : ObjectId("5ebfd02b3a3b38a52be0460c"), "item" : "postcard", "qty" : 45, "tags" : [ "blue" ], "dim_cm" : [ 10, 15.25 ] }

以下两个查询都没有结果：

> db.inventory.find( { size: { h: { $gt: 14 } }  } )
> 
> db.inventory.find( { size: { $elemMatch: {  h: { $gt: 14 } } } } )

而有一个大于 14 的文档：

{ "_id" : ObjectId("5eb67598bee5213484d4508a"), "item" : "planner", "qty" : 0, "status" : "D", "size" : { "h" : 22.85, "w" : 30, "uom" : "cm" }, "tags" : [ "blank", "red" ] }

以下语法不起作用： > db.inventory.find( { size.h: { $gt: 14 } } ) 2020-05-24T15:08:44.306+0530 E QUERY [js] uncaught exception: SyntaxError: missing : after property id :@(shell):1:25 `

请解释原因。

【问题讨论】：

标签： database mongodb nosql

【解决方案1】：

您需要在查询嵌套文档时添加点表示法。你可以试试这个

db.inventory.find( { 'size.h': { $gt: 14 } } )

【讨论】：