mongoDB数据库基本操作
> db.student.ensureIndex({name:1}){
"createdCollectionAutomatically" : false,
"numIndexesBefore" : 1,
"numIndexesAfter" : 2,
"ok" : 1
}
> db.student.getIndexes() //查看索引
[
{
"v" : 1,
"key" : {
"_id" : 1
},
"name" : "_id_",
"ns" : "studentdb.student"
},
{
"v" : 1,
"key" : {
"name" : 1
},
"name" : "name_1",
"ns" : "studentdb.student"
}
]
> db.student.ensureIndex({name:1,age:1})
{
"createdCollectionAutomatically" : false,
"numIndexesBefore" : 2,
"numIndexesAfter" : 3,
"ok" : 1
}
> db.student.getIndexes()
[
{
"v" : 1,
"key" : {
"_id" : 1
},
"name" : "_id_",
"ns" : "studentdb.student"
},
{
"v" : 1,
"key" : {
"name" : 1
},
"name" : "name_1",
"ns" : "studentdb.student"
},
{
"v" : 1,
"key" : {
"name" : 1,
"age" : 1
},
"name" : "name_1_age_1",
"ns" : "studentdb.student"
}
]
> db.student.ensureIndex({name:1,age:-11})
{
"createdCollectionAutomatically" : false,
"numIndexesBefore" : 3,
"numIndexesAfter" : 4,
"ok" : 1
}
> db.student.getIndexes()
[
{
"v" : 1,
"key" : {
"_id" : 1
},
"name" : "_id_",
"ns" : "studentdb.student"
},
{
"v" : 1,
"key" : {
"name" : 1
},
"name" : "name_1",
"ns" : "studentdb.student"
},
{
"v" : 1,
"key" : {
"name" : 1,
"age" : 1
},
"name" : "name_1_age_1",
"ns" : "studentdb.student"
},
{
"v" : 1,
"key" : {
"name" : 1,
"age" : -11
},
"name" : "name_1_age_-11",
"ns" : "studentdb.student"
}
]
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