查询MongoDB的子集以获取记录
您可以使用$all运算符。首先让我们创建一个包含文档的集合-
> db.subsetOfAnArrayDemo.insertOne({"StudentProgrammingSkills":
["Java","MongoDB","MySQL","C++","Data Structure","Algorithm","Python","Oracle","SQL Server"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cb9d1e1895c4fd159f80804")
}以下是在find()方法的帮助下显示集合中所有文档的查询-
> db.subsetOfAnArrayDemo.find().pretty();
这将产生以下输出-
{
"_id" : ObjectId("5cb9d1e1895c4fd159f80804"),
"StudentProgrammingSkills" : [
"Java",
"MongoDB",
"MySQL",
"C++",
"Data Structure",
"Algorithm",
"Python",
"Oracle",
"SQL Server"
]
}以下是获取数组子集的查询-
> db.subsetOfAnArrayDemo.find({ StudentProgrammingSkills:
{ $all: [ 'MongoDB', 'MySQL' ] } } ).pretty();这将产生以下输出-
{
"_id" : ObjectId("5cb9d1e1895c4fd159f80804"),
"StudentProgrammingSkills" : [
"Java",
"MongoDB",
"MySQL",
"C++",
"Data Structure",
"Algorithm",
"Python",
"Oracle",
"SQL Server"
]
}