查詢其子集時獲取 MongoDB 中的記錄
可以使用 $all 運算子。我們首先建立一個包含文件的集合 −
> db.subsetOfAnArrayDemo.insertOne({"StudentProgrammingSkills":
["Java","MongoDB","MySQL","C++","Data Structure","Algorithm","Python","Oracle","SQL Server"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cb9d1e1895c4fd159f80804")
}以下是查詢,以用 find() 方法顯示集合中的所有文件 −
> db.subsetOfAnArrayDemo.find().pretty();
這會產生以下輸出 −
{
"_id" : ObjectId("5cb9d1e1895c4fd159f80804"),
"StudentProgrammingSkills" : [
"Java",
"MongoDB",
"MySQL",
"C++",
"Data Structure",
"Algorithm",
"Python",
"Oracle",
"SQL Server"
]
}以下是獲取陣列子集的查詢 −
> db.subsetOfAnArrayDemo.find({ StudentProgrammingSkills:
{ $all: [ 'MongoDB', 'MySQL' ] } } ).pretty();這會產生以下輸出 −
{
"_id" : ObjectId("5cb9d1e1895c4fd159f80804"),
"StudentProgrammingSkills" : [
"Java",
"MongoDB",
"MySQL",
"C++",
"Data Structure",
"Algorithm",
"Python",
"Oracle",
"SQL Server"
]
}
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