如何在 MongoDB 中将字符串转换为数值?
mongodbdatabasebig data analytics
您需要使用一些代码才能在 MongoDB 中将字符串转换为数值。
首先，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.convertStringToNumberDemo.insertOne({"EmployeeId":"101","EmployeeName":"Larry"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c7f56528d10a061296a3c31")
}
> db.convertStringToNumberDemo.insertOne({"EmployeeId":"1120","EmployeeName":"Mike"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c7f56648d10a061296a3c32")
}
> db.convertStringToNumberDemo.insertOne({"EmployeeId":"3210","EmployeeName":"Sam"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c7f566e8d10a061296a3c33")
}
使用 find() 方法显示集合中的所有文档。查询如下 −
> db.convertStringToNumberDemo.find().pretty();
以下是输出 −
{
"_id" : ObjectId("5c7f56528d10a061296a3c31"),
"EmployeeId" : "101",
"EmployeeName" : "Larry"
}
{
"_id" : ObjectId("5c7f56648d10a061296a3c32"),
"EmployeeId" : "1120",
"EmployeeName" : "Mike"
}
{
"_id" : ObjectId("5c7f566e8d10a061296a3c33"),
"EmployeeId" : "3210",
"EmployeeName" : "Sam"
}
以下是在 MongoDB 中将字符串转换为数值的查询。将"EmployeeId"字符串转换为数值。查询如下 −
> db.convertStringToNumberDemo.find().forEach(function(x)
... {
... db.convertStringToNumberDemo.update
... (
...
... {
... "_id": x._id,
...
... },
... {
... "$set":
... {
... "EmployeeId": parseInt(x.EmployeeId)
... }
... }
... )
... }
... );
现在检查集合中的文档。查询如下 −
> db.convertStringToNumberDemo.find().pretty();
以下输出显示了将字符串值 (EmployeeId) 转换为整数后的结果 −
{
"_id" : ObjectId("5c7f56528d10a061296a3c31"),
"EmployeeId" : 101,
"EmployeeName" : "Larry"
}
{
"_id" : ObjectId("5c7f56648d10a061296a3c32"),
"EmployeeId" : 1120,
"EmployeeName" : "Mike"
}
{
"_id" : ObjectId("5c7f566e8d10a061296a3c33"),
"EmployeeId" : 3210,
"EmployeeName" : "Sam"
}
