在MongoDB 4中进行嵌套查询以获取特定文档
对于嵌套查询，让我们首先创建包含文档的集合-
> db.demo492.insertOne({
... "ProductDetails" :
... {
... "StockDetails" : [
... { "ProductName" : "Product-1" },
... {"ProductName" : "Product-2"},
... { "ProductName" : "Product-3"}
...
... ]
...
... }
... });
{
"acknowledged" : true,
"insertedId" : ObjectId("5e849db8b0f3fa88e22790c2")
}
>
>
>
> db.demo492.insertOne({
... "ProductDetails" :
... {
... "StockDetails" : [
... { "ProductName" : "Product-4" },
... {"ProductName" : "Product-5"},
... { "ProductName" : "Product-6"}
...
... ]
...
... }
... });
{
"acknowledged" : true,
"insertedId" : ObjectId("5e849dceb0f3fa88e22790c3")
}在find()方法的帮助下显示集合中的所有文档-
> db.demo492.find();
这将产生以下输出-
{ "_id" : ObjectId("5e849db8b0f3fa88e22790c2"), "ProductDetails" : { "StockDetails" : [ {
"ProductName" : "Product-1" }, { "ProductName" : "Product-2" }, { "ProductName" : "Product3" } ] } }
{ "_id" : ObjectId("5e849dceb0f3fa88e22790c3"), "ProductDetails" : { "StockDetails" : [ {
"ProductName" : "Product-4" }, { "ProductName" : "Product-5" }, { "ProductName" : "Product6" } ] } }以下显示在MongoDB中使用点表示法来获取特定文档的嵌套查询-
> db.demo492.find({ "ProductDetails.StockDetails.ProductName":"Product-1"});这将产生以下输出-
{ "_id" : ObjectId("5e849db8b0f3fa88e22790c2"), "ProductDetails" : { "StockDetails" : [ {
"ProductName" : "Product-1" }, { "ProductName" : "Product-2" }, { "ProductName" : "Product3" } ] } }