MONGOLDB CRUD Operations

> Db.user.insert ({username: ' Gugang '}) Writeresult ({"ninserted": 1}) > Db.user.insert ({username: ' Jones '})  Writeresult ({"ninserted": 1}) > Db.user.find () {"_id": ObjectId ("59454e7b961eb6f4b52b675f"), "username": "Gugang"  } {"_id": ObjectId ("59454e85961eb6f4b52b6760"), "username": "Jones"} > Db.user.find ({username: ' Gugang '}) {"_id": ObjectId ("59454e7b961eb6f4b52b675f"), "username": "Gugang"} > Db.user.find ({username: ' Jones '}) {"_id": ObjectId (" 59454e85961eb6f4b52b6760 ")," username ":" Jones "} > Db.user.find ({username: ' Gugang '}). Pretty () {" _id ": ObjectId ("
59454e7b961eb6f4b52b675f ")," username ":" Gugang "} > Db.user.find ({$or: [{Username:gugang}, {username:jones}]}) 2017-06-17t23:47:15.381+0800 E QUERY [Thread1] Referenceerror:gugang is not defined: @ (Shell): 1:21 > Db.user.find (
{$or: [{username: ' Gugang '}, {username: ' Jones '}]}
{"_id": ObjectId ("59454e7b961eb6f4b52b675f"), "username": "Gugang"} {"_id": ObjectId ("59454e85961eb6f4b52b6760")," username ":" Jones "} > Db.user.find ({$and: [{username: ' Gugang '}, {username: ' Jones '}]}) > Db.user.find ({$and:
[{username: ' Gugang '}, {id: ' 59454e7b961eb6f4b52b675f '}]} > Db.user.find ({$and: [{username: ' Gugang '}, {-id: ' 59454e7b961eb6f4b52b675f '}]}) 2017-06-18t00:06:14.006+0800 E QUERY [Thread1] Syntaxerror:invalid Property ID @ (Shell): 1:42 > Db.user.find ({$and: [{username: ' Gugang '}, {_id: ' 5945 4e7b961eb6f4b52b675f '}}) > Db.user.find ({$and: [{username: ' Gugang '}, {_id:objectid ("59454e7b961eb6f4b52b675f") }]} {"_id": ObjectId ("59454e7b961eb6f4b52b675f"), "username": "Gugang"} > Db.user.find ({_id: ' 59454e7b961eb6f4b52b675f '}) 2017-06-18t00:06:59.288+0800 E QUERY [Thread1] syntaxerror:missing; Before statement @ (Shell): 1:46 > Db.user.find ({' _id ': ' 59454e7b961eb6f4b52b675f '})) 2017-06-18t00:07:12.677+0800 E QUERY [Thread1] syntaxerror:missing; Before statement @ (Shell): 1:48 > Db.user.find ({$and: [{username: ' Gugang '}, {_id:objectid ("59454e7b961eb6f4b52b675f "}]}) {" _id ": ObjectId (" 59454e7b961eb6f4b52b675f ")," username ":" Gugang "} > Db.user.find ({' _id ': '})) 2017-06-1 8t00:07:32.374+0800 E QUERY [Thread1] syntaxerror:missing;
Before statement @ (Shell): 1:24 > Db.user.find ({' _id ': '} ') > Db.user.find ({' _id ': ' 59454e7b961eb6f4b52b675f '}) > Db.user.insert ({_id:1, username: ' Hello '}) Writeresult ({"ninserted": 1}) > Db.user.find ({' _id ': '}) > Db.use R.find ({}) {"_id": ObjectId ("59454e7b961eb6f4b52b675f"), "username": "Gugang"} {"_id": ObjectId ("59454e85961eb6f4b52 b6760 ")," username ":" Jones "} {" _id ": 1," username ":" Hello "} > Db.user.find ({_id:1}) {" _id ": 1," username ":"  Hello "} > Db.user.update ({username: ' Gugang '}, {$set: {county:" ""}}) Writeresult ({"nmatched": 1, "nupserted": 0, "Nmodified": 1}) > Db.user.find ({username: ' Gugang '}) {"_id": ObjectId ("59454e7b961eb6f4b52b675f"), "username": "G Ugang "," County ":" > Db.user.update "({username: ' Gugang '}, {county: ' Canada '}) WriTeresult ({"nmatched": 1, "nupserted": 0, "nmodified": 1}) > Db.user.find ({username: ' Gugang '}) > Db.user.find ({} {"_id": ObjectId ("59454e7b961eb6f4b52b675f"), "County": "Canada"} {"_id": ObjectId ("59454e85961eb6f4b52b6760"), "U Sername ":" Jones "} {" _id ": 1," username ":" Hello "} > Db.user.update ({County: ' Canada '}, {$set: {username: ' Gugang ') }}) Writeresult ({"nmatched": 1, "nupserted": 0, "nmodified": 1}) > Db.user.find ({username: ' Gugang '}) {"_id": OBJ Ectid ("59454e7b961eb6f4b52b675f"), "County": "Canada", "username": "Gugang"} > Db.user.update ({username: ' Gugang '} {$unset: {county:1}}) Writeresult ({"nmatched": 1, "nupserted": 0, "nmodified": 1}) > Db.user.find ({username: ' gu Gang '}} {"_id": ObjectId ("59454e7b961eb6f4b52b675f"), "username": "Gugang"} > Db.user.insert ({username: ' Gavin '}) W Riteresult ({"ninserted": 1}) > Db.user.find ({username: ' Gavin '}) {"_id": ObjectId ("59455576961eb6f4b52b6761"), "us Ername ":" Gavin "} > Db.uSer.update ({username: ' Gavin '}, {$set: {favorites:{cities:[' Beijing ', ' Tianjin '], movies: [' The Sting ', ' Casablanca ']} }}) Writeresult ({"nmatched": 1, "nupserted": 0, "nmodified": 1}) > Db.user.find ({username: ' Gavin '}). Pretty () {"_ ID ": ObjectId (" 59455576961eb6f4b52b6761 ")," username ":" Gavin "," Favorites ": {" Cities ": [" Beijing "," Tianj In "]," movies ": [" The Sting "," Casablanca "]}} > Db.user.find ({username: ' Gugang '}) {" _id ": ObjectId ("59454e7b961eb6f4b52b675f"), "username": "Gugang"} > Db.user.update ({username: ' Gugang '}, {$set: {favorites: {Citi es:[' Shanghai ', ' Chengdu '}}} writeresult ({"nmatched": 1, "nupserted": 0, "nmodified": 1}) > Db.user.find ({Userna Me: ' Gugang '}). Pertty () 2017-06-18t00:22:04.565+0800 E QUERY [thread1] TypeError:db.user.find (...). Pertty is not a function: @ (Shell): 1:1 > Db.user.find ({username: ' Gugang '}). Pretty () {"_id": ObjectId ("59454e7b961eb 6f4b52b675f ")," username ":" Gugang "," favoriTEs ': {"Cities": ["Shanghai", "Chengdu"]} > Db.user.update ({username: ' Gugang '}, {$addToSet: {' Favorit Es.cities ': ' Beijing '}}, False, True) Writeresult ({"nmatched": 1, "nupserted": 0, "nmodified": 1}) > Db.user.find ({ Username: ' Gugang '}). Pretty () {"_id": ObjectId ("59454e7b961eb6f4b52b675f"), "username": "Gugang", "Favorites": {" Cities ": [Shanghai", "Chengdu", "Beijing"]}} > Db.user.find () {"_id": ObjectId ("59454e7b961eb6f4b52 b675f ")," username ":" Gugang "," Favorites ": {" Cities ": [" Shanghai "," Chengdu "," Beijing "]}} {" _id ": ObjectId (" 59 454e85961eb6f4b52b6760 ")," username ":" Jones "} {" _id ": 1," username ":" Hello "} {" _id ": ObjectId (" 59455576961eb6f4b 52b6761 ")," username ":" Gavin "," Favorites ": {" Cities ": [" Beijing "," Tianjin "]," movies ": [" The Sting "," Casablanc A ']} > Db.user.remove ({_id:1}) Writeresult ({"nremoved": 1}) > Db.user.find () {"_id": ObjectId ("59454e7b961e b6f4b52b675f ")," UsernamE ":" Gugang "," Favorites ": {" Cities ": [" Shanghai "," Chengdu "," Beijing "]} {" _id ": ObjectId (" 59454e85961eb6f4b52 b6760 ")," username ":" Jones "} {" _id ": ObjectId (" 59455576961eb6f4b52b6761 ")," username ":" Gavin "," Favorites ": {" CIT IES ": [" Beijing "," Tianjin "]," movies ": [" The Sting "," Casablanca "]}} > Db.user.remove () 2017-06-18t00:27:57.16 9+0800 E QUERY [thread1] error:remove needs a QUERY:DBCOLLECTION.PROTOTYPE._PARSEREMOVE@SRC/MONGO/SHELL/COLLECTION.J S:409:1 dbcollection.prototype.remove@src/mongo/shell/collection.js:434:18 @ (Shell): 1:1 > Db.user.find () {"_id":  ObjectId ("59454e7b961eb6f4b52b675f"), "username": "Gugang", "Favorites": {"Cities": ["Shanghai", "Chengdu", "Beijing" ]} {"_id": ObjectId ("59454e85961eb6f4b52b6760"), "username": "Jones"} {"_id": ObjectId ("59455576961eb6f4b52b6761 ")," username ":" Gavin "," Favorites ": {" Cities ": [" Beijing "," Tianjin "]," movies ": [" The Sting "," Casablanca "]} } > Db.user.remove ({}) WrIteresult ({"Nremoved": 3}) > Db.user.find () >  

> Show Tables
user
> Db.user.drop ()
true
> Show Tables
> Db.help ()