修改数据
修改里面还有查询条件。你要该谁，要告诉 mongo。
查找名字叫做小明的，把年龄更改为 16 岁：
1 db.student.update({"name":"小明"},{$set:{"age":16}});
查找数学成绩是 70，把年龄更改为 33 岁：
1 db.student.update({"score.shuxue":70},{$set:{"age":33}});
更改所有匹配项目："
By default, the update() method updates a single document. To update multiple documents, use
the multi option in the update() method.
1 db.student.update({"sex":"男"},{$set:{"age":33}},{multi: true});
完整替换，不出现$set 关键字了： 注意
1 db.student.update({"name":"小明"},{"name":"大明","age":16});
db.users.update({name: 'Lisi'}, {$inc: {age: 50}}, false, true);
相当于：update users set age = age + 50 where name = ‘Lisi’;
db.users.update({name: 'Lisi'}, {$inc: {age: 50}, $set: {name: 'hoho'}}, false, true);
相当于：update users set age = age + 50, name = ‘hoho’ where name = ‘Lisi’;
删除数据
db.collectionsNames.remove( { "borough": "Manhattan" } )
db.users.remove({age: 132});
By default, the remove() method removes all documents that match the remove condition. Use
the justOne option to limit the remove operation to only one of the matching documents.
db.restaurants.remove( { "borough": "Queens" }, { justOne: true } )