Merge pull request #21883 from taosdata/docs/TD-24855

docs: fix document error for unique and sample
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dapan1121 2023-06-28 16:13:59 +08:00 committed by GitHub
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2 changed files with 8 additions and 16 deletions

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@ -998,18 +998,14 @@ SAMPLE(expr, k)
**Description**: _k_ sampling values of a specific column. The applicable range of _k_ is [1,1000].
**Return value type**: Same as the column being operated plus the associated timestamp
**Return value type**: Same as the column being operated
**Applicable data types**: Any data type except for tags of STable
**Applicable data types**: Any data type
**Applicable nested query**: Inner query and Outer query
**Applicable table types**: standard tables and supertables
**More explanations**:
- This function cannot be used in expression calculation.
### TAIL
@ -1054,11 +1050,11 @@ TOP(expr, k)
UNIQUE(expr)
```
**Description**: The values that occur the first time in the specified column. The effect is similar to `distinct` keyword, but it can also be used to match tags or timestamp. The first occurrence of a timestamp or tag is used.
**Description**: The values that occur the first time in the specified column. The effect is similar to `distinct` keyword.
**Return value type**:Same as the data type of the column being operated upon
**Applicable column types**: Any data types except for timestamp
**Applicable column types**: Any data types
**Applicable table types**: table, STable

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@ -990,18 +990,14 @@ SAMPLE(expr, k)
**功能说明** 获取数据的 k 个采样值。参数 k 的合法输入范围是 1≤ k ≤ 1000。
**返回结果类型** 同原始数据类型 返回结果中带有该行记录的时间戳
**返回结果类型** 同原始数据类型。
**适用数据类型** 在超级表查询中使用时,不能应用在标签之上
**适用数据类型** 全部类型字段
**嵌套子查询支持** 适用于内层查询和外层查询。
**适用于**:表和超级表。
**使用说明**
- 不能参与表达式计算;该函数可以应用在普通表和超级表上;
### TAIL
@ -1046,11 +1042,11 @@ TOP(expr, k)
UNIQUE(expr)
```
**功能说明**:返回该列的数值首次出现的值。该函数功能与 distinct 相似,但是可以匹配标签和时间戳信息。可以针对除时间列以外的字段进行查询,可以匹配标签和时间戳,其中的标签和时间戳是第一次出现时刻的标签和时间戳
**功能说明**:返回该列数据首次出现的值。该函数功能与 distinct 相似。
**返回数据类型**:同应用的字段。
**适用数据类型**适合于除时间类型以外的字段。
**适用数据类型**全部类型字段。
**适用于**: 表和超级表。