> For the complete documentation index, see [llms.txt](https://docs.mongoing.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.mongoing.com/can-kao/yun-suan-fu/aggregation-pipeline-operators/and-aggregation.md).

# $and (aggregation)

在本页面

* [定义](#definition)
* [行为](#behavior)
* [例子](#examples)

## 定义

**$and**

计算一个或多个表达式，如果所有表达式都为`true`，或者如果没有参数表达式调用，则返回`true`。否则，`$and`返回`false`。

`$and` 具有以下语法：

```
{ $and: [ <expression1>, <expression2>, ... ] }
```

有关表达式的更多信息，请参见 表达式。

## 行为

`$and`使用短路逻辑：遇到第一个`false`表达式后，运算将停止评估。

除了`false`布尔值，`$and`计算为`false`如下：`null`，`0`，和`undefined` 的值。在`$and`评估所有其它值`true`，包括非零数值和阵列。

| 例子                                           | 结果   |
| -------------------------------------------- | ---- |
| { $and: \[ 1, "green" ] }                    | true |
| { $and: \[ ] }                               | true |
| { $and: \[ \[ null ], \[ false ], \[ 0 ] ] } | true |
| { $and: \[ null, true ] }                    | true |
| { $and: \[ 0, true ] }                       | true |

## 例子

`inventory`使用以下文档创建示例集合：

```
db.inventory.insertMany([
   { "_id" : 1, "item" : "abc1", description: "product 1", qty: 300 },
   { "_id" : 2, "item" : "abc2", description: "product 2", qty: 200 },
   { "_id" : 3, "item" : "xyz1", description: "product 3", qty: 250 },
   { "_id" : 4, "item" : "VWZ1", description: "product 4", qty: 300 },
   { "_id" : 5, "item" : "VWZ2", description: "product 5", qty: 180 }
])
```

以下操作使用`$and`运算符确定是否`qty`大于100 \_并\_小于`250`：

```
db.inventory.aggregate(
   [
     {
       $project:
          {
            item: 1,
            qty: 1,
            result: { $and: [ { $gt: [ "$qty", 100 ] }, { $lt: [ "$qty", 250 ] } ] }
          }
     }
   ]
)
```

该操作返回以下结果：

```
{ "_id" : 1, "item" : "abc1", "qty" : 300, "result" : false }
{ "_id" : 2, "item" : "abc2", "qty" : 200, "result" : true }
{ "_id" : 3, "item" : "xyz1", "qty" : 250, "result" : false }
{ "_id" : 4, "item" : "VWZ1", "qty" : 300, "result" : false }
{ "_id" : 5, "item" : "VWZ2", "qty" : 180, "result" : true }
```

译者：李冠飞

校对：


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://docs.mongoing.com/can-kao/yun-suan-fu/aggregation-pipeline-operators/and-aggregation.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.