> ## 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.

> 计算算术平均值。

# avg

<div id="avg">
  ## avg
</div>

引入版本：v1.1.0

计算算术平均值。

**语法**

```sql theme={null}
avg(x)
```

**参数**

* `x` — 输入值。[`(U)Int*`](/zh/reference/data-types/int-uint) 或 [`Float*`](/zh/reference/data-types/float) 或 [`Decimal`](/zh/reference/data-types/decimal)

**返回值**

返回算术平均值；如果输入参数 `x` 为空，则返回 `NaN`。[`Float64`](/zh/reference/data-types/float)

**示例**

**基本用法**

```sql title=Query theme={null}
SELECT avg(x) FROM VALUES('x Int8', 0, 1, 2, 3, 4, 5);
```

```response title=Response theme={null}
┌─avg(x)─┐
│    2.5 │
└────────┘
```

**空表会返回 NaN**

```sql title=Query theme={null}
CREATE TABLE test (t UInt8) ENGINE = Memory;

SELECT avg(t) FROM test;
```

```response title=Response theme={null}
┌─avg(x)─┐
│    nan │
└────────┘
```