数据删除

db.集合.remove(删除条件,是否只删除一个数据);

默认删多条(false)

true删除一条

db.集合.remove({}) 删除所有元素

但集合还在

db.集合.drop() 删除集合

游标

指数据可以一行行的进行操作,类似ResultSet数据处理

在mongo里是需要使用find()就可以返回游标了

对于操作返回的游标,可使用函数操作

1.判断是否有下一行数据:hasNext()

2.取当前数据: next()

var cur=db.web.find();

cur.hasNext();

cur.next();

> db.web.find();{ "_id" : ObjectId("592c945f997b7830e7f76d05"), "lan" : "php7", "need" : [ "mysql", "js", "html", "css", "tp", "yii" ] }{ "_id" : ObjectId("592c945f997b7830e7f76d06"), "lan" : "jav  a", "need" : [ "mysql", "js", "html", "css", "oracle", "spring" ] }{ "_id" : ObjectId("592c945f997b7830e7f76d07"), "lan" : "python", "need" : [ "mysql", "js", "html", "css", "flask" ] }{ "_id" : ObjectId("592c945f997b7830e7f76d08"), "lan" : "PythoN", "need" : [ "mysql", "js", "html", "css", "flask", "diagno" ] }> var cur=db.web.find();> cur.hasNext();true> cur.next();{    "_id" : ObjectId("592c945f997b7830e7f76d05"),    "lan" : "php7",    "need" : [        "mysql",        "js",        "html",        "css",        "tp",        "yii"    ]}var cur=db.web.find();while(cur.hasNext()){    var p=cur.next();    print(p.lan);}> var cur=db.web.find();> while(cur.hasNext()){... var p=cur.next();... print(p.lan);... }php7jav  apythonPythoN

p是object

如果需要输出json

可使用printjson()

> var cur=db.web.find();> while(cur.hasNext()){... var p=cur.next();... print(p);... }[object BSON][object BSON][object BSON][object BSON]var cur=db.web.find();while(cur.hasNext()){    var p=cur.next();    printjson(p);}