MongoDB(2)shell命令操作数据库 2查询
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? ?db.collections(名称).find;返回 的是find function 的结构
? ? function (query, fields, limit, skip) {
return new DBQuery(this._mongo, this._db, this, this._fullName, this._massageObject(query), fields, limit, skip);}?
? ? 第一个参数 是查询条件 ，第二个是 指定字段 ，第三个是数量，第四个是起点
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/**
?????? 查询
???????
**/
db.order.find();//相当于select *from order
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db.order.find({name:'lisa'});//相当于 select * from order where order.name=’lisa’?
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db.order.find({id:{$gt:2}});//相当于select *from order where order.id>2 ?
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db.order.find({id:{$gte:2}})//相当于 select *from order where order.id>=2?
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db.order.find({id:{$gte:2,$lte:4}})// select *from order where id>=2 and id<=4;?
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db.order.find({name:/e/}) // select *from order where name like ‘%e%’?
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db.order.find({name:/^lee/}) //select *from order where name like ‘lee%‘?
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db.order.find({},{name:1,id:1}) //指定 id， name为搜索自动 select id,name from order?
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db.order.find({id:{$gt:2}},{id:1,name:1});//select id ,name from order where id >2;?
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db.order.find().sort({id:1}); //select *from order order by id asc ?
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db.order.find().sort({id:-1}); //select *from order order by id desc?
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db.order.find({name:/e/,id:{$gte:2}});// select *from order where name like ‘%e%’ and id >=2?
db.order.find().limit(3);// select top 3 *from order;
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db.order.find().limit(10).skip(5);// 分页 limit 一页取多少条 skip 起始页 select *from order limit 50,60
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db.order.find({$or:[{id:2},{id:5}]});// or与 查询select *from order where id=2 or id=5?
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db.order.findOne(); //查询第一条数据select top 1 *from order;
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db.order.find({id:{$gt:2}}).count();//查询某个结果集的记录条数select count(*) from order where id>2
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db.order.find({name:{$exists:true}}).count();//按照某列进行排序select count(name) from order
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db.order.ensureIndex({name:1}) // 创建索引?
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db.order.totalIndexSize(); //查看总索引记录大小
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db.order.getIndexes();//查看当前的所有索引
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db.order.dropIndex('name_1')//删除指定索引?
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db.order.dropIndexes();//删除所有索引