> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-fix-nav-issues.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

> JSONColumns 格式文档

# JSONColumns

| 输入 | 输出 | 别名 |
| -- | -- | -- |
| ✔  | ✔  |    |

<div id="description">
  ## 说明
</div>

<Tip>
  JSONColumns\* 格式的输出会先给出 ClickHouse 字段名，然后列出该字段在表中各行的内容；
  直观来看，数据相当于向左旋转了 90 度。
</Tip>

在这种格式中，所有数据都表示为一个 JSON Object。

<Note>
  `JSONColumns` 格式会先在内存中缓冲所有数据，再将其作为单个块输出，因此可能导致较高的内存占用。
</Note>

<div id="example-usage">
  ## 使用示例
</div>

<div id="inserting-data">
  ### 插入数据
</div>

使用一个名为 `football.json` 的 JSON 文件，其内容如下：

```json theme={null}
{
    "date": ["2022-04-30", "2022-04-30", "2022-04-30", "2022-05-02", "2022-05-02", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07"],
    "season": [2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021],
    "home_team": ["Sutton United", "Swindon Town", "Tranmere Rovers", "Port Vale", "Salford City", "Barrow", "Bradford City", "Bristol Rovers", "Exeter City", "Harrogate Town A.F.C.", "Hartlepool United", "Leyton Orient", "Mansfield Town", "Newport County", "Oldham Athletic", "Stevenage Borough", "Walsall"],
    "away_team": ["Bradford City", "Barrow", "Oldham Athletic", "Newport County", "Mansfield Town", "Northampton Town", "Carlisle United", "Scunthorpe United", "Port Vale", "Sutton United", "Colchester United", "Tranmere Rovers", "Forest Green Rovers", "Rochdale", "Crawley Town", "Salford City", "Swindon Town"],
    "home_team_goals": [1, 2, 2, 1, 2, 1, 2, 7, 0, 0, 0, 0, 2, 0, 3, 4, 0],
    "away_team_goals": [4, 1, 0, 2, 2, 3, 0, 0, 1, 2, 2, 1, 2, 2, 3, 2, 3]
}
```

插入数据：

```sql theme={null}
INSERT INTO football FROM INFILE 'football.json' FORMAT JSONColumns;
```

<div id="reading-data">
  ### 读取数据
</div>

使用 `JSONColumns` 格式读取数据：

```sql theme={null}
SELECT *
FROM football
FORMAT JSONColumns
```

输出将为 JSON 格式：

```json theme={null}
{
    "date": ["2022-04-30", "2022-04-30", "2022-04-30", "2022-05-02", "2022-05-02", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07"],
    "season": [2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021],
    "home_team": ["Sutton United", "Swindon Town", "Tranmere Rovers", "Port Vale", "Salford City", "Barrow", "Bradford City", "Bristol Rovers", "Exeter City", "Harrogate Town A.F.C.", "Hartlepool United", "Leyton Orient", "Mansfield Town", "Newport County", "Oldham Athletic", "Stevenage Borough", "Walsall"],
    "away_team": ["Bradford City", "Barrow", "Oldham Athletic", "Newport County", "Mansfield Town", "Northampton Town", "Carlisle United", "Scunthorpe United", "Port Vale", "Sutton United", "Colchester United", "Tranmere Rovers", "Forest Green Rovers", "Rochdale", "Crawley Town", "Salford City", "Swindon Town"],
    "home_team_goals": [1, 2, 2, 1, 2, 1, 2, 7, 0, 0, 0, 0, 2, 0, 3, 4, 0],
    "away_team_goals": [4, 1, 0, 2, 2, 3, 0, 0, 1, 2, 2, 1, 2, 2, 3, 2, 3]
}
```

<div id="format-settings">
  ## 格式设置
</div>

导入时，如果将 [`input_format_skip_unknown_fields`](/zh/reference/settings/formats#input_format_skip_unknown_fields) 设置为 `1`，则会跳过名称未知的列。
块中不存在的列将填充为默认值 (此处可使用 [`input_format_defaults_for_omitted_fields`](/zh/reference/settings/formats#input_format_defaults_for_omitted_fields) 设置)