更新MongoDB中数组内的元素？
要更新数组中的元素，请在MongoDB中使用$set。让我们创建一个包含文档的集合-
> db.demo494.insertOne(
... {
...
... "CollegeDetails" : [
... {
... "CollegeName" : "MIT",
... "Fees" : 80000
... },
... {
... "CollegeName" : "SU",
... "Fees" : 90000
... }
... ]
... }
... )
{
"acknowledged" : true,
"insertedId" : ObjectId("5e84a5c1b0f3fa88e22790c9")
}在find()方法的帮助下显示集合中的所有文档-
> db.demo494.find().pretty();
这将产生以下输出-
{
"_id" : ObjectId("5e84a5c1b0f3fa88e22790c9"),
"CollegeDetails" : [
{
"CollegeName" : "MIT",
"Fees" : 80000
},
{
"CollegeName" : "SU",
"Fees" : 90000
}
]
}以下是更新MongoDB中数组内元素的查询-
> db.demo494.update(
...
... {
... "CollegeDetails.CollegeName": "MIT"
... },
...
... {
... $set:
... {
... "CollegeDetails.$.Fees" : 100000
... }
... }
... );
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })在find()方法的帮助下显示集合中的所有文档-
> db.demo494.find().pretty();
这将产生以下输出-
{
"_id" : ObjectId("5e84a5c1b0f3fa88e22790c9"),
"CollegeDetails" : [
{
"CollegeName" : "MIT",
"Fees" : 100000
},
{
"CollegeName" : "SU",
"Fees" : 90000
}
]
}