MongoDB database common commands
1. Help to view the command prompt
help
db.help()
db.test.help()
db.test.find().help()
2. Create/switch database
> use music
switched to db music
3. Query the database
> show dbs
admin 0.000GB
config 0.000GB
local 0.000GB
4. View the currently used database
> db
music
# 或
> db.getName()
music
5. Display the current DB status
> db.stats()
{
"db" : "music",
"collections" : 0,
"views" : 0,
"objects" : 0,
"avgObjSize" : 0,
"dataSize" : 0,
"storageSize" : 0,
"totalSize" : 0,
"indexes" : 0,
"indexSize" : 0,
"scaleFactor" : 1,
"fileSize" : 0,
"fsUsedSize" : 0,
"fsTotalSize" : 0,
"ok" : 1
}
6. View the current DB version
db.version()
7. View the link machine address of the current DB
> db.getMongo()
connection to 127.0.0.1:27017
8. Delete the database
> db.dropDatabase()
{
"ok" : 1 }
Collection collection operations
1. Create a collection
db.createCollection("singer", {
size: 20, capped: true, max: 100});
2. Determine whether the set has a fixed capacity
> db.singer.isCapped()
true
3. Get the collection with the specified name
db.getCollection("account")
MongoDB delete collection
db.collection.drop()
4. Get all the collections of the current db
> db.getCollectionNames()
[ "album", "singer" ]
5. Display the status of all collections in the current db
db.printCollectionStats()
document manipulation
query all records
> db.singer.find()
{
"_id" : ObjectId("622a15791181c7388318c06f"), "name" : "张三", "age" : 25 }
{
"_id" : ObjectId("622a158d1181c7388318c071"), "name" : "zhangsan", "age" : 25, "sex" : true }
{
"_id" : ObjectId("622a15961181c7388318c072"), "name" : "zhangsan", "age" : 25, "sex" : true }
Insert document
save
> db.singer.save({
name: 'zhangsan', age: 25, sex: '男'})
WriteResult({
"nInserted" : 1 })
> db.singer.find()
{
"_id" : ObjectId("622a158d1181c7388318c071"), "name" : "zhangsan", "age" : 25, "sex" : '男' }
insert
> db.singer.insert([{
name: '老王', age: 40}, {
name: '老李', age: 30}])
BulkWriteResult({
"writeErrors" : [ ],
"writeConcernErrors" : [ ],
"nInserted" : 2,
"nUpserted" : 0,
"nMatched" : 0,
"nModified" : 0,
"nRemoved" : 0,
"upserted" : [ ]
})
> db.singer.find()
{
"_id" : ObjectId("622a17d61181c7388318c077"), "name" : "老王", "age" : 40 }
{
"_id" : ObjectId("622a17d61181c7388318c078"), "name" : "老李", "age" : 30 }
insertOne
> db.singer.insertOne({
name: '李四'})
{
"acknowledged" : true,
"insertedId" : ObjectId("622a16d51181c7388318c075")
}
> db.singer.find()
{
"_id" : ObjectId("622a16bb1181c7388318c074"), "name" : "李四" }
insertMany
> db.singer.insertMany([{
name: '小王', age: 20}, {
name: '小李', age: 20}])
{
"acknowledged" : true,
"insertedIds" : [
ObjectId("622a18c1e53b1497cfd6d1a3"),
ObjectId("622a18c1e53b1497cfd6d1a4")
]
}
> db.singer.find()
{
"_id" : ObjectId("622a18c1e53b1497cfd6d1a3"), "name" : "小王", "age" : 20 }
{
"_id" : ObjectId("622a18c1e53b1497cfd6d1a4"), "name" : "小李", "age" : 20 }
Modify the document update()
The update() method is used to update an existing document. The syntax format is as follows:
db.collection.update(
<query>,
<update>,
{
upsert: <boolean>,
multi: <boolean>,
writeConcern: <document>
}
)
Parameter Description:
- query : The query condition for update, similar to the where in the sql update query.
- update : the object of the update and some update operators (like , ,, inc...), etc., can also be understood as the set after the sql update query
- upsert : optional, this parameter means, if there is no updated record, whether to insert objNew, true is the insertion, the default is false, not inserted.
- multi : optional, mongodb defaults to false, only the first record found is updated, if this parameter is true, all the records found by the condition are updated.
- writeConcern : optional, the level of exception thrown.
$set modification
db.singer.update({
age: 25}, {
$set: {
name: 'changeName'}}, false, true);
# 相当于：
update singer set name = 'changeName' where age = 25;
$inc increments
db.singer.update({
name: 'Lisi'}, {
$inc: {
age: 50}}, false, true);
# 相当于：
update singer set age = age + 50 where name = 'Lisi';
db.singer.update({
name: 'Lisi'}, {
$inc: {
age: 50}, $set: {
name: 'hoho'}}, false, true);
# 相当于：
update singer set age = age + 50, name = 'hoho' where name = 'Lisi';
delete document
db.singer.remove({
age: 132});