笔记 | MongoDB

### 查询条件
#### 简单条件
db. 集合名 .find({key: "值" })
db. 集合名 .find({key: "值", keyname: "值" })

```
> db.student.find({"name" : "小乔"}, {name: 1, age: 1, sex: 1})
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a0"), "name" : "小乔", "age" : 18, "sex" : false }

> db.student.find({"age" : 23, "sex": true}, {name: 1, age: 1, sex: 1})
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a4"), "name" : "张良", "age" : 23, "sex" : true }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a6"), "name" : "黄忠", "age" : 23, "sex" : true }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a7"), "name" : "杨戬", "age" : 23, "sex" : true }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97ac"), "name" : "刘婵", "age" : 23, "sex" : true }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97ad"), "name" : "jim", "age" : 23, "sex" : true }
```

#### 范围比较
$in 在…里

```
> db.student.find({"age" : {$in: [18, 24]}}, {name: 1, age: 1, sex: 1})
{ "_id" : ObjectId("602a0cc35cea5b7cb50d9796"), "name" : "李信", "age" : 24, "sex" : true }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d979c"), "name" : "关羽", "age" : 24, "sex" : true }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d979d"), "name" : "周瑜", "age" : 24, "sex" : true }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a0"), "name" : "小乔", "age" : 18, "sex" : false }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a5"), "name" : "哪吒", "age" : 18, "sex" : true }
```

$nin 不在…里
$or 或

```
# 使用$or查询指定数据
> db.student.find({$or:[{"name" : "张良"}, {"name" : "哪吒"}]})
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a4"), "name" : "张良", "age" : 23, "sex" : true, "class" : 202002, "course" : [ "python", "web" ] }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a5"), "name" : "哪吒", "age" : 18, "sex" : true, "class" : 202001, "course" : [ "python", "web" ] }

# 使用$or修改指定数据
> db.student.update({$or:[{"name" : "张良"}, {"name" : "哪吒"}]}, {$set:{"class" : 202002}},{multi:true})
WriteResult({ "nMatched" : 2 "nUpserted" : 0, "nModified" : 2})

# 使用$or查询指定数据
> db.student.find({$or:[{"name" : "露娜"}, {"name" : "黄忠"}]})
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a6"), "name" : "黄忠", "age" : 23, "sex" : true, "class" : 202001, "course" : [ "python", "web" ] }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a8"), "name" : "露娜", "age" : 23, "sex" : false, "class" : 202001, "course" : [ "python", "web" ] }

# 使用$or修改指定数据
> db.student.update({$or:[{"name" : "露娜"}, {"name" : "黄忠"}]}, {$set:{"class" : 202003},{multi:true})
WriteResult({ "nMatched" : 2, "nUpserted" : 0, "nModified" : 2 })

# 使用$nin方法查询
> db.student.find({"class" : {$nin: [202001, 202002]}}, {name: 1, age: 1, sex: 1})
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a6"), "name" : "黄忠", "age" : 23, "sex" : true }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a8"), "name" : "露娜", "age" : 23, "sex" : false }
```

#### 正则匹配
MongoDB 使用 $regex 操作符来设置匹配字符串的正则表达式。
MongoDB使用PCRE (Perl Compatible Regular Expression) 作为正则表达式语言。

```
# 插入数据
> db.student.insert({"name": "李斯", "age" : 26, "sex" : true, "class" : 202003, "course" : [ "python", "web" ]})
WriteResult({ "nInserted" : 1 })

# 使用正则表达式查询
> db.student.find({name: {$regex: "李"}}, {name: 1, age: 1, sex: 1})
{ "_id" : ObjectId("602a0cc35cea5b7cb50d9796"), "name" : "李信", "age" : 24, "sex" : true }
{ "_id" : ObjectId("602a1e9a5cea5b7cb50d97ae"), "name" : "李斯", "age" : 26, "sex" : true }

# 也可以写为
> db.student.find({name: /^李/}, {name: 1, age: 1, sex: 1})
{ "_id" : ObjectId("602a0cc35cea5b7cb50d9796"), "name" : "李信", "age" : 24, "sex" : true }
{ "_id" : ObjectId("602a1e9a5cea5b7cb50d97ae"), "name" : "李斯", "age" : 26, "sex" : true }
```

#### 数值比较
等于

- {<key>:<value>}

```
> db.student.find({"name" : "韩信"}, {name: 1, age: 1, sex: 1})
{ "_id" : ObjectId("602a0cc35cea5b7cb50d9799"), "name" : "韩信", "age" : 22, "sex" : true }
```

小于
- {<key>:{$lt:<value>}}

```
> db.student.find({age: {$lt: 19}}, {name: 1, age: 1, sex: 1})
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a0"), "name" : "小乔", "age" : 18, "sex" : false }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a5"), "name" : "哪吒", "age" : 18, "sex" : true }
```

小于或等于
- {<key>:{$lte:<value>}}

```
> db.student.update({"name": "嫦娥"}, {$set:{age: 19}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

> db.student.find({age: {$lte: 19}}, {name: 1, age: 1, sex: 1})
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a0"), "name" : "小乔", "age" : 18, "sex" : false }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a2"), "name" : "嫦娥", "age" : 19, "sex" : false }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a5"), "name" : "哪吒", "age" : 18, "sex" : true }
```

大于
- {<key>:{$gt:<value>}}

```
> db.student.find({age: {$gt: 37}}, {name: 1, age: 1, sex: 1})
{ "_id" : ObjectId("602a0cc35cea5b7cb50d979f"), "name" : "曹操", "age" : 43, "sex" : true }
```

大于或等于
- {<key>:{$gte:<value>}}

```
> db.student.find({age: {$gte: 37}}, {name: 1, age: 1, sex: 1})
{ "_id" : ObjectId("602a0cc35cea5b7cb50d9794"), "name" : "鲁班", "age" : 37, "sex" : true }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d979b"), "name" : "亚瑟", "age" : 37, "sex" : true }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d979f"), "name" : "曹操", "age" : 43, "sex" : true }
```

不等于
- {<key>:{$ne:<value>}}

```
> db.student.find({"age" : 37, "name": {$ne:"鲁班"}}, {name: 1, age: 1, sex: 1})
{ "_id" : ObjectId("602a0cc35cea5b7cb50d979b"), "name" : "亚瑟", "age" : 37, "sex" : true }
```

#### MongoDB AND 条件
MongoDB 的 find() 方法可以传入多个键(key)，每个键(key)以逗号隔开，即常规 SQL 的 AND 条件

```
> db.student.find({"age" : 23, "class" : 202001}, {name: 1, age: 1, sex: 1})
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a3"), "name" : "西施", "age" : 23, "sex" : false }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a7"), "name" : "杨戬", "age" : 23, "sex" : true }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97a9"), "name" : "貂蝉", "age" : 23, "sex" : false }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97aa"), "name" : "芈月", "age" : 23, "sex" : false }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97ab"), "name" : "妲己", "age" : 23, "sex" : false }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97ac"), "name" : "刘婵", "age" : 23, "sex" : true }
{ "_id" : ObjectId("602a0cc35cea5b7cb50d97ad"), "name" : "jim", "age" : 23, "sex" : true }
```

#### 匹配 null , 也可以匹配没有的字段
db.集合名.find({key1:null, key2:null})

晓松

MongoDB 查询条件

MongoDB 常见条件使用

晓松

MongoDB 查询条件 MongoDB 常见条件使用

MongoDB 查询条件

MongoDB 常见条件使用