如何使用 MongoDB 统计仅匹配两个字段的集合?
mongodbdatabasebig data analytics更新于 2026/2/14 19:52:17
要统计仅匹配两个字段的集合，请使用 count()。让我们创建一个包含文档的集合 −
> db.demo175.insertOne({"EmployeeName":"Bob","isMarried":"YES"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3840969e4f06af551997e8")
}
> db.demo175.insertOne({"EmployeeName":"David","isMarried":"NO"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e38409e9e4f06af551997e9")
}
> db.demo175.insertOne({"EmployeeName":"Mike","isMarried":"YES"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3840a79e4f06af551997ea")
}
> db.demo175.insertOne({"EmployeeName":"Sam","isMarried":"NO"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3840ae9e4f06af551997eb")
}
借助 find() 方法显示集合中的所有文档 −
> db.demo175.find();
这将产生以下输出 −
{ "_id" : ObjectId("5e3840969e4f06af551997e8"), "EmployeeName" : "Bob", "isMarried" : "YES" }
{ "_id" : ObjectId("5e38409e9e4f06af551997e9"), "EmployeeName" : "David", "isMarried" : "NO" }
{ "_id" : ObjectId("5e3840a79e4f06af551997ea"), "EmployeeName" : "Mike", "isMarried" : "YES" }
{ "_id" : ObjectId("5e3840ae9e4f06af551997eb"), "EmployeeName" : "Sam", "isMarried" : "NO" }
以下查询仅计算与两个字段匹配的集合 −
> db.demo175.count( { "EmployeeName": "Mike", "isMarried":"YES" } );
这将产生以下输出 −
1
