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65 lines
920 B
Markdown
65 lines
920 B
Markdown
---
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toc_priority: 5
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---
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# avg {#agg_function-avg}
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计算算术平均值。
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**语法**
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``` sql
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avg(x)
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```
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**参数**
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- `x` — 输入值, 必须是 [Integer](../../../sql-reference/data-types/int-uint.md), [Float](../../../sql-reference/data-types/float.md), 或 [Decimal](../../../sql-reference/data-types/decimal.md)。
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**返回值**
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- 算术平均值，总是 [Float64](../../../sql-reference/data-types/float.md) 类型。
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- 输入参数 `x` 为空时返回 `NaN` 。
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**示例**
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查询:
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``` sql
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SELECT avg(x) FROM values('x Int8', 0, 1, 2, 3, 4, 5);
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```
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结果:
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``` text
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┌─avg(x)─┐
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│ 2.5 │
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└────────┘
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```
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**示例**
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创建一个临时表:
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查询:
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``` sql
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CREATE table test (t UInt8) ENGINE = Memory;
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```
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获取算术平均值:
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查询:
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```
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SELECT avg(t) FROM test;
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```
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结果:
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``` text
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┌─avg(x)─┐
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│ nan │
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└────────┘
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```
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