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57 lines
1.3 KiB
Markdown
57 lines
1.3 KiB
Markdown
---
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slug: /en/sql-reference/aggregate-functions/reference/stddevpop
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sidebar_position: 188
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---
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# stddevPop
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The result is equal to the square root of [varPop](../../../sql-reference/aggregate-functions/reference/varpop.md).
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Aliases: `STD`, `STDDEV_POP`.
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:::note
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This function uses a numerically unstable algorithm. If you need [numerical stability](https://en.wikipedia.org/wiki/Numerical_stability) in calculations, use the [`stddevPopStable`](../reference/stddevpopstable.md) function. It works slower but provides a lower computational error.
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:::
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**Syntax**
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```sql
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stddevPop(x)
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```
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**Parameters**
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- `x`: Population of values to find the standard deviation of. [(U)Int*](../../data-types/int-uint.md), [Float*](../../data-types/float.md), [Decimal*](../../data-types/decimal.md).
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**Returned value**
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- Square root of standard deviation of `x`. [Float64](../../data-types/float.md).
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**Example**
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Query:
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```sql
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DROP TABLE IF EXISTS test_data;
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CREATE TABLE test_data
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(
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population UInt8,
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)
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ENGINE = Log;
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INSERT INTO test_data VALUES (3),(3),(3),(4),(4),(5),(5),(7),(11),(15);
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SELECT
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stddevPop(population) AS stddev
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FROM test_data;
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```
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Result:
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```response
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┌────────────stddev─┐
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│ 3.794733192202055 │
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└───────────────────┘
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```
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