查找数组字段不为空的 MongoDB 记录?
mongodbdatabasebig data analytics更新于 2026/1/19 9:22:17
您可以使用 $ne(不等于)运算符来实现此目的。为了理解这个概念，让我们创建一个包含文档的集合。创建包含文档的集合的查询如下: −
> db.arrayFieldIsNotEmptyDemo.insertOne({"StudentName":"Larry","StudentTechnicalSubject":["Java","C"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c76fe2f1e9c5dd6f1f78291")
}
> db.arrayFieldIsNotEmptyDemo.insertOne({"StudentName":"Mike","StudentTechnicalSubject":[]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c76fe3b1e9c5dd6f1f78292")
}
> db.arrayFieldIsNotEmptyDemo.insertOne({"StudentName":"Sam","StudentTechnicalSubject":["MongoDB"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c76fe491e9c5dd6f1f78293")
}
> db.arrayFieldIsNotEmptyDemo.insertOne({"StudentName":"Carol","StudentTechnicalSubject":[]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c76fe521e9c5dd6f1f78294")
}
> db.arrayFieldIsNotEmptyDemo.insertOne({"StudentName":"David","StudentTechnicalSubject":["MySQL","SQL Server"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c76fe661e9c5dd6f1f78295")
}
使用 find() 方法显示集合中的所有文档。查询如下 −
> db.arrayFieldIsNotEmptyDemo.find().pretty();
输出
{
"_id" : ObjectId("5c76fe2f1e9c5dd6f1f78291"),
"StudentName" : "Larry",
"StudentTechnicalSubject" : [
"Java",
"C"
]
}
{
"_id" : ObjectId("5c76fe3b1e9c5dd6f1f78292"),
"StudentName" : "Mike",
"StudentTechnicalSubject" : [ ]
}
{
"_id" : ObjectId("5c76fe491e9c5dd6f1f78293"),
"StudentName" : "Sam",
"StudentTechnicalSubject" : [
"MongoDB"
]
}
{
"_id" : ObjectId("5c76fe521e9c5dd6f1f78294"),
"StudentName" : "Carol",
"StudentTechnicalSubject" : [ ]
}
{
"_id" : ObjectId("5c76fe661e9c5dd6f1f78295"),
"StudentName" : "David",
"StudentTechnicalSubject" : [
"MySQL",
"SQL Server"
]
}
以下查询用于查找数组字段不为空的 MongoDB 记录 −
> db.arrayFieldIsNotEmptyDemo.find({StudentTechnicalSubject:{$exists:true,$ne:[]}}).pretty();
输出
{
"_id" : ObjectId("5c76fe2f1e9c5dd6f1f78291"),
"StudentName" : "Larry",
"StudentTechnicalSubject" : [
"Java",
"C"
]
}
{
"_id" : ObjectId("5c76fe491e9c5dd6f1f78293"),
"StudentName" : "Sam",
"StudentTechnicalSubject" : [
"MongoDB"
]
}
{
"_id" : ObjectId("5c76fe661e9c5dd6f1f78295"),
"StudentName" : "David",
"StudentTechnicalSubject" : [
"MySQL",
"SQL Server"
]
}
