db.user.find().limit(10).skip(5);
可用于分页,limit 是 pageSize,skip 是(page-1)*pageSize
18、or 与 查询
db.user.find({$or: [{age: 22}, {age: 25}]});
相当于:select * from user where age = 22 or age = 25;
19、findOne 查询第一条数据
db.user.findOne();
相当于:selecttop 1 * from user;
db.user.find().limit(1);
20、查询某个结果集的记录条数 统计数量
db.user.find({age: {$gte: 25}}).count();
相当于:select count(*) from user where age >= 20;
如果要返回限制之后的记录数量,要使用 count(true)或者 count(非 0)
db.users.find().skip(10).limit(5).count(true);
四、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’;
五、 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 } )