如何使用 $ne 运算符查询 MongoDB？
要使用$ne运算符查询MongoDB，以下是语法-
db.yourCollectionName.find({yourFieldName:{$ne:yourValue}}).pretty();让我们创建一个包含文档的集合-
> db.notEqaulToDemo.insertOne({"StudentName":"Larry","StudentMathMarks":68});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cbd3a6bde8cc557214c0ded")
}
> db.notEqaulToDemo.insertOne({"StudentName":"Chris","StudentMathMarks":88});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cbd3a79de8cc557214c0dee")
}
> db.notEqaulToDemo.insertOne({"StudentName":"David","StudentMathMarks":45});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cbd3a89de8cc557214c0def")
}
> db.notEqaulToDemo.insertOne({"StudentName":"Carol","StudentMathMarks":69});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cbd3a97de8cc557214c0df0")
}借助find()方法显示集合中的所有文档-
> db.notEqaulToDemo.find().pretty();
这将产生以下输出-
{
"_id" : ObjectId("5cbd3a6bde8cc557214c0ded"),
"StudentName" : "Larry",
"StudentMathMarks" : 68
}
{
"_id" : ObjectId("5cbd3a79de8cc557214c0dee"),
"StudentName" : "Chris",
"StudentMathMarks" : 88
}
{
"_id" : ObjectId("5cbd3a89de8cc557214c0def"),
"StudentName" : "David",
"StudentMathMarks" : 45
}
{
"_id" : ObjectId("5cbd3a97de8cc557214c0df0"),
"StudentName" : "Carol",
"StudentMathMarks" : 69
}以下是对MongoDB$ne运算符的查询-
> db.notEqaulToDemo.find({StudentMathMarks:{$ne:88}}).pretty();这将产生以下输出-
{
"_id" : ObjectId("5cbd3a6bde8cc557214c0ded"),
"StudentName" : "Larry",
"StudentMathMarks" : 68
}
{
"_id" : ObjectId("5cbd3a89de8cc557214c0def"),
"StudentName" : "David",
"StudentMathMarks" : 45
}
{
"_id" : ObjectId("5cbd3a97de8cc557214c0df0"),
"StudentName" : "Carol",
"StudentMathMarks" : 69
}