?????????????

???????????????????db.tablename.remove??{???}?? ??????????????У?????? “google”?????????????

????> db.users.remove({username:"google"})

????> db.users.find()

????{ "_id" : ObjectId("504f45cd17f6c778042c3c07")?? "password" : "hello123"?? "username" : "mkyong" }

???????db.tablename.remove??????????????????м????

?????????????db.tablename.drop???? ??

????8. Indexing

???????????

???????????????????????????????

????8.1 List all indexes of table “users”?? by default the column “_id” is always the primary key and created automatically.

????8.1??????“???”?????????￡????е???????“_id”????????????????????

> db.users.getIndexes()
[
{
"v" : 1??
"key" : {
"_id" : 1
}??
"ns" : "mkyong.users"??
"name" : "_id_"
}
]
>

????8.2???????????????db.tablename.ensureIndex???У???????????????У?“?????”?????????????

> db.users.ensureIndex({username:1})
> db.users.getIndexes()
[
{
"v" : 1??
"key" : {
"_id" : 1
}??
"ns" : "mkyong.users"??
"name" : "_id_"
}??
{
"v" : 1??
"key" : {
"username" : 1
}??
"ns" : "mkyong.users"??
"name" : "username_1"
}
]

????8.3????????????db.tablename.dropIndex???У???????????????У?“?????”??????????????????


> db.users.dropIndex({username:1})
{ "nIndexesWas" : 2?? "ok" : 1 }
> db.users.getIndexes()
[
{
"v" : 1??
"key" : {
"_id" : 1
}??
"ns" : "mkyong.users"??
"name" : "_id_"
}
]
>

????8.4?????????????????db.tablename.ensureIndex??{??}??{???????????}?? ??????????????У?“?????”?????????????

> db.users.ensureIndex({username:1}??{unique:true});
> db.users.getIndexes()
[
{
"v" : 1??
"key" : {
"_id" : 1
}??
"ns" : "mkyong.users"??
"name" : "_id_"
}??
{
"v" : 1??
"key" : {
"username" : 1
}??
"unique" : true??
"ns" : "mkyong.users"??
"name" : "username_1"
}
]