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法律研究仅显示MongoDB文档中特定薪资的员工姓名，且文档包含员工记录？
若要仅显示特定薪资的员工姓名，请在MongoDB $in 中设置薪资并提取姓名。让我们创建一个包含以下文档的集合
> db.demo666.insertOne({"EmployeeName":"John","EmployeeSalary":25000});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ea1c04824113ea5458c7d0d")
}
> db.demo666.insertOne({"EmployeeName":"Chris","EmployeeSalary":35000});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ea1c05524113ea5458c7d0e")
}
> db.demo666.insertOne({"EmployeeName":"David","EmployeeSalary":65000});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ea1c06024113ea5458c7d0f")
}
> db.demo666.insertOne({"EmployeeName":"Carol","EmployeeSalary":40000});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ea1c06f24113ea5458c7d10")
}使用find()方法显示某个集合中的所有文档−
> db.demo666.find();
这将产生以下输出 −
{ "_id" : ObjectId("5ea1c04824113ea5458c7d0d"), "EmployeeName" : "John", "EmployeeSalary" : 25000 }
{ "_id" : ObjectId("5ea1c05524113ea5458c7d0e"), "EmployeeName" : "Chris", "EmployeeSalary" : 35000 }
{ "_id" : ObjectId("5ea1c06024113ea5458c7d0f"), "EmployeeName" : "David", "EmployeeSalary" : 65000 }
{ "_id" : ObjectId("5ea1c06f24113ea5458c7d10"), "EmployeeName" : "Carol", "EmployeeSalary" : 40000 }以下是使用$in并提取特定薪资员工姓名的查询−
> db.demo666.find({"EmployeeSalary":{$in:[35000,40000]}},{_id:0,"EmployeeSalary":0});这将产生以下输出 −
{ "EmployeeName" : "Chris" }
{ "EmployeeName" : "Carol" }
更新时间：13-5-2020
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