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法学如何在 MongoDB 中获取游标的值？
若要在 MongoDB 中获取游标的值，请使用 hasNext()。让我们使用文档创建一个集合 -
> db.demo191.insertOne({"EmployeeId":1,"EmployeeName":"Chris Brown"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3ad95303d395bdc21346c5")
}
> db.demo191.insertOne({"EmployeeId":2,"EmployeeName":"David Miller"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3ad95f03d395bdc21346c6")
}
> db.demo191.insertOne({"EmployeeId":1,"EmployeeName":"John Doe"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3ad96803d395bdc21346c7")
}
> db.demo191.insertOne({"EmployeeId":1,"EmployeeName":"John Smith"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3ad97003d395bdc21346c8")
}使用 find() 方法显示集合中的所有文档 -
> db.demo191.find();
这将产生以下输出 -
{ "_id" : ObjectId("5e3ad95303d395bdc21346c5"), "EmployeeId" : 1, "EmployeeName" : "Chris Brown" }
{ "_id" : ObjectId("5e3ad95f03d395bdc21346c6"), "EmployeeId" : 2, "EmployeeName" : "David Miller" }
{ "_id" : ObjectId("5e3ad96803d395bdc21346c7"), "EmployeeId" : 1, "EmployeeName" : "John Doe" }
{ "_id" : ObjectId("5e3ad97003d395bdc21346c8"), "EmployeeId" : 1, "EmployeeName" : "John Smith" }以下是获取游标对象的值的查询 -
> var cursor = db.demo191.find( { "EmployeeId":1 } );
> while (cursor.hasNext()) {
... print(tojson(cursor.next()));
...}这将产生以下输出 -
{
"_id" : ObjectId("5e3ad95303d395bdc21346c5"),
"EmployeeId" : 1,
"EmployeeName" : "Chris Brown"
}
{
"_id" : ObjectId("5e3ad96803d395bdc21346c7"),
"EmployeeId" : 1,
"EmployeeName" : "John Doe"
}
{
"_id" : ObjectId("5e3ad97003d395bdc21346c8"),
"EmployeeId" : 1,
"EmployeeName" : "John Smith"
}
更新于: 27-Mar-2020
587 次浏览
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