mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-11-17 21:24:28 +00:00
63 lines
876 B
Markdown
63 lines
876 B
Markdown
---
|
|
toc_priority: 5
|
|
---
|
|
|
|
# avg {#agg_function-avg}
|
|
|
|
计算算术平均值。
|
|
|
|
**语法**
|
|
|
|
``` sql
|
|
avg(x)
|
|
```
|
|
|
|
**参数**
|
|
|
|
- `x` — 列名
|
|
|
|
`x` 必须是
|
|
[Integer](../../../sql-reference/data-types/int-uint.md),
|
|
[floating-point](../../../sql-reference/data-types/float.md), or
|
|
[Decimal](../../../sql-reference/data-types/decimal.md).
|
|
|
|
**返回值**
|
|
|
|
- `NaN`。 参数列为空时返回。
|
|
- 算术平均值。 其他情况。
|
|
|
|
**返回类型** 总是 [Float64](../../../sql-reference/data-types/float.md).
|
|
|
|
**示例**
|
|
|
|
查询:
|
|
|
|
``` sql
|
|
SELECT avg(x) FROM values('x Int8', 0, 1, 2, 3, 4, 5)
|
|
```
|
|
|
|
结果:
|
|
|
|
``` text
|
|
┌─avg(x)─┐
|
|
│ 2.5 │
|
|
└────────┘
|
|
```
|
|
|
|
**示例**
|
|
|
|
查询:
|
|
|
|
``` sql
|
|
CREATE table test (t UInt8) ENGINE = Memory;
|
|
SELECT avg(t) FROM test
|
|
```
|
|
|
|
结果:
|
|
|
|
``` text
|
|
┌─avg(x)─┐
|
|
│ nan │
|
|
└────────┘
|
|
```
|