mongodb basic

[henryliangt]

https://mongoosejs.com/ JS backend library

cd C:\Program Files\MongoDB\Server\4.0\bin mongod --dbpath E:\software\MongoDB\data

cd C:\MongoDB\Server\3.2\bin mongod --config C:\MongoDB\Server\3.2\mongod.cfg

[henryliangt]

mongo show dbs use show collections db.collectionName.find()

[henryliangt]

https://www.cnblogs.com/fayin/p/6656445.html https://blog.imdst.com/mongodb-chang-yong-shellming-ling-zheng-li/

use city_data show collections

db.climate_original.find().count()

//相当于%% db.climate_original.find({region: /Australia/}); db.climate_original.find({region: {$ne:'Australia'}}).count();

db.climate_original.find({region: {$ne:'Australia'}}, {region: 1});

db.climate_original.find({region: {$ne:'Australia'}}, {region: 1, city: 1}).sort({'region': 1});

db.climate_original.find({$and:[{region: {$ne:'Australia'}}, {city: {$exists: true}}]}, {region: 1, city: 1}).sort({'region': 1}) ;

db.climate_original.find({$and:[{region: {$ne:'Australia'}}, {city: {$exists: true}}]}, {region: 1, city: 1}).sort({'region': 1}).count();

[henryliangt]

https://docs.mongoing.com/mongodb-crud-operations/query-documents/query-an-array

db.climate_original.find( { "monthlyAvg.1.snowDays": { $lt: 1 } } ).count();

db.climate_original.find( { "monthlyAvg.1.snowDays": { $lt: 1 } },{city: 1} ).sort({'monthlyAvg.1.snowDays' : 1}).count()

https://blog.csdn.net/leshami/article/details/55049891

[henryliangt]

db.climate_original.find({city: /^A/}, {city: 1, region: 1});

db.climate_original.find({city: /^A/}).count(); https://www.mongodb.com/docs/manual/tutorial/project-fields-from-query-results/

[henryliangt]

db.climate_original.find().s( { "monthlyAvg.2.snowDays": { $lt: 1 } } );

db.climate_original.find({},{city:1 , monthlyAvg.4.rainfall:1 , '_id': 0 }).sort({"monthlyAvg.4.rainfall":-1}).limit(5); db.climate_original.find({},{city:1, '_id': 0}).sort({"monthlyAvg.4.rainfall":-1}).limit(10);

db.climate_original.find({},{city:1 , monthlyAvg.3.rainfall:1 , '_id': 0 }).sort({"monthlyAvg.3.rainfall":-1}).limit(5);

db.climate_original.find({},{city:1, '_id': 0}).sort({"monthlyAvg.3.rainfall":-1}).limit(5);

[henryliangt]

db.climate_original.find( { "monthlyAvg.6.high": { $gt: 32 } }, { city :1 } ); db.climate_original.find( { "monthlyAvg.6.high": { $gt: 32 } }, { city :1 , '_id':0 , monthlyAvg:1 } );

db.climate_original.find( { "monthlyAvg.7.high": { $gt: 32 } }, { city :1 } );

db.climate_original.find( { $or: [ {"monthlyAvg.6.high": { $gt: 32 } } , {"monthlyAvg.7.high": { $gt: 32} } ] );

db.climate_original.find( {$or: [{'monthlyAvg.6.high':{$gt:32}}, {"monthlyAvg.7.high": {$gt: 32}}]}, {city:1}).count();

db.climate_original.find( {$or: [{'monthlyAvg.6.high':{$gt:32}}, {"monthlyAvg.7.high": {$gt: 32}} ,{"monthlyAvg.7.high": {$gt: 32}}]}, {city:1}).count();

db.climate_original.find( { $or : [ {"monthlyAvg.6.high": { $gt: 32 } } , {"monthlyAvg.7.high": { $gt: 32 } } , {"monthlyAvg.8.high": { $gt: 32 } } ] );

db.climate_original.find( {$or: [{'monthlyAvg.6.high':{$gt:32}}, {"monthlyAvg.7.high": {$gt: 32}} ,{"monthlyAvg.7.high": {$gt: 32}}]}, {city:1});

[henryliangt]

db.climate_original.insert({"air_cond_needed":""})

[henryliangt]

db.climate_original.update( { "_id" : { $gt : 0 } } , { $set : { "air_cond_needed" : 1} },false,true ); db.climate_original.find()

June July August

db.climate_original.update( {$or: [{'monthlyAvg.5.high':{$gt:32}}, {"monthlyAvg.6.high": {$gt: 32}} ,{"monthlyAvg.7.high": {$gt: 32}}]}, { $set : { "air_cond_needed" : "yes"} },false,true );

[henryliangt]

db.climate_original.find( { "monthlyAvg.7.high": { $gt: 32 } }, { city :1 , air_cond_needed: 1} );

db.climate_original.find( { $or: [{'monthlyAvg.5.high':{$gt:32}}, {"monthlyAvg.6.high": {$gt: 32}} ,{"monthlyAvg.7.high": {$gt: 32}}] }, { city :1 , air_cond_needed: 1} );

db.climate_original.find( { $or: [{'monthlyAvg.5.high':{$gt:32}}, {"monthlyAvg.6.high": {$gt: 32}} ,{"monthlyAvg.7.high": {$gt: 32}}] }, { city :1 , air_cond_needed: 1} ).count();