> For the complete documentation index, see [llms.txt](https://goooqo.docs.doyto.win/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://goooqo.docs.doyto.win/zh/query-mapping/query-object/subquery-field.md).

# 子查询字段

对于一般的子查询条件，例如`score > (SELECT avg(score) FROM t_user WHERE removed = ?)`，在OQM中被分为三个部分分别进行映射：

* score >
* SELECT avg(score) FROM t\_user
* WHERE clause

第一部分`score >`， 可以使用字段名`scoreGtXxx`来映射得到。 谓词后缀之后定义的字符串仅用于区分重复的字段名，在映射时会被忽略。

第二部分包含一个列名和一个表名，这些属于不变的静态，GoooQo提供了两种标签来保存这些信息： 一种是标签`subquery`，用于定义该子查询语句； 一种是标签`select`和`from`的组合，分别保存列名和表名。

第三部分是另一个WHERE子句，可以通过查询对象来映射。因此，我们将字段类型定义为对应的查询对象，并通过查询对象映射方法将字段的值映射为子查询中WHERE子句。

### 示例（v0.2.0+）

```go
ScoreLtAvg *UserQuery `subquery:"select avg(score) from User"`
ScoreLtAny *UserQuery `subquery:"SELECT score FROM User"`
ScoreLtAll *UserQuery `subquery:"select score from User"`
ScoreGtAvg *UserQuery `select:"avg(score)" from:"User"`
```


---

# 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://goooqo.docs.doyto.win/zh/query-mapping/query-object/subquery-field.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.