用MongoDB替换数组字段值？
您可以使用位置运算符$。首先让我们创建一个包含文档的集合-
> db.replaceAnArrayFieldValueDemo.insertOne({"StudentTechnicalSubjects":["MySQL","SQL Server","PL/SQL"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cea41e0ef71edecf6a1f68f")
}以下是在find()方法的帮助下显示集合中所有文档的查询-
> db.replaceAnArrayFieldValueDemo.find().pretty();
这将产生以下输出-
{
"_id" : ObjectId("5cea41e0ef71edecf6a1f68f"),
"StudentTechnicalSubjects" : [
"MySQL",
"SQL Server",
"PL/SQL"
]
}以下是替换数组字段值的查询。在这里，我们使用“MongoDB”更新“SQLServer”-
> db.replaceAnArrayFieldValueDemo.update(
{"StudentTechnicalSubjects":"SQL Server"},
{ $set: { 'StudentTechnicalSubjects.$': "MongoDB" }}
);
WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 })让我们再次检查文档-
> db.replaceAnArrayFieldValueDemo.find().pretty();
这将产生以下输出-
{
"_id" : ObjectId("5cea41e0ef71edecf6a1f68f"),
"StudentTechnicalSubjects" : [
"MySQL",
"MongoDB",
"PL/SQL"
]
}