diff --git a/src/UserGuide/Master/Table/SQL-Manual/Basis-Function.md b/src/UserGuide/Master/Table/SQL-Manual/Basis-Function.md index 328f7fa84..98f992ba0 100644 --- a/src/UserGuide/Master/Table/SQL-Manual/Basis-Function.md +++ b/src/UserGuide/Master/Table/SQL-Manual/Basis-Function.md @@ -119,6 +119,33 @@ Example 3: Query records where region is not 'Beijing' or 'Shanghai' SELECT * FROM table1 WHERE region NOT IN ('Beijing', 'Shanghai'); ``` +### 1.5 GREATEST and LEAST + +The `GREATEST` function returns the maximum value from a list of arguments, while the `LEAST` function returns the minimum value. The return type matches the input data type. + +Key Behaviors: +1. NULL Handling: Returns NULL if all arguments are NULL. +2. Parameter Requirements: Requires at least 2 arguments. +3. Type Constraints: All arguments must have the same data type. +4. Supported Types: `BOOLEAN`、`FLOAT`、`DOUBLE`、`INT32`、`INT64`、`STRING`、`TEXT`、`TIMESTAMP`、`DATE` + +**Syntax:** + +```sql + greatest(value1, value2, ..., valueN) + least(value1, value2, ..., valueN) +``` + +**Examples:** + +```sql +-- Retrieve the maximum value between `temperature` and `humidity` in `table2` +SELECT GREATEST(temperature,humidity) FROM table2; + +-- Retrieve the minimum value between `temperature` and `humidity` in `table2` +SELECT LEAST(temperature,humidity) FROM table2; +``` + ## 2. Aggregate functions ### 2.1 Overview @@ -127,29 +154,31 @@ SELECT * FROM table1 WHERE region NOT IN ('Beijing', 'Shanghai'); 2. Except for `COUNT()`, all other aggregate functions ignore null values and return null when there are no input rows or all values are null. For example, `SUM()` returns null instead of zero, and `AVG()` does not include null values in the count. -### 2.2 Supported Aggregate Functions - -| Function Name | Description | Allowed Input Types | Output Type | -| :------------ | :----------------------------------------------------------- | :------------------------- | :----------------------------------------- | -| COUNT | Counts the number of data points. | All types | INT64 | -| SUM | Calculates the sum. | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| AVG | Calculates the average. | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| MAX | Finds the maximum value. | All types | Same as input type | -| MIN | Finds the minimum value. | All types | Same as input type | -| FIRST | Finds the value with the smallest timestamp that is not NULL. | All types | Same as input type | -| LAST | Finds the value with the largest timestamp that is not NULL. | All types | Same as input type | -| STDDEV | Alias for STDDEV_SAMP, calculates the sample standard deviation. | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| STDDEV_POP | Calculates the population standard deviation. | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| STDDEV_SAMP | Calculates the sample standard deviation. | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| VARIANCE | Alias for VAR_SAMP, calculates the sample variance. | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| VAR_POP | Calculates the population variance. | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| VAR_SAMP | Calculates the sample variance. | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| EXTREME | Finds the value with the largest absolute value. If the largest absolute values of positive and negative values are equal, returns the positive value. | INT32 INT64 FLOAT DOUBLE | Same as input type | -| MODE | Finds the mode. Note: 1. There is a risk of memory exception when the number of distinct values in the input sequence is too large; 2. If all elements have the same frequency, i.e., there is no mode, a random element is returned; 3. If there are multiple modes, a random mode is returned; 4. NULL values are also counted in frequency, so even if not all values in the input sequence are NULL, the final result may still be NULL. | All types | Same as input type | -| MAX_BY | MAX_BY(x, y) finds the value of x corresponding to the maximum y in the binary input x and y. MAX_BY(time, x) returns the timestamp when x is at its maximum. | x and y can be of any type | Same as the data type of the first input x | -| MIN_BY | MIN_BY(x, y) finds the value of x corresponding to the minimum y in the binary input x and y. MIN_BY(time, x) returns the timestamp when x is at its minimum. | x and y can be of any type | Same as the data type of the first input x | -| FIRST_BY | FIRST_BY(x, y) finds the value of x in the same row when y is the first non-null value. | x and y can be of any type | Same as the data type of the first input x | -| LAST_BY | LAST_BY(x, y) finds the value of x in the same row when y is the last non-null value. | x and y can be of any type | Same as the data type of the first input x | +### 2.2 Supported Aggregate Functions + +| Function Name | Description | Allowed Input Types | Output Type | +|:--------------|:---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|:-------------------------------------------------------------------|:-------------------------------------------| +| COUNT | Counts the number of data points. | All types | INT64 | +| COUNT_IF | COUNT_IF(exp) counts the number of rows that satisfy a specified boolean expression. | `exp` must be a boolean expression,(e.g. `count_if(temperature>20)`) | INT64 | +| SUM | Calculates the sum. | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| AVG | Calculates the average. | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| MAX | Finds the maximum value. | All types | Same as input type | +| MIN | Finds the minimum value. | All types | Same as input type | +| FIRST | Finds the value with the smallest timestamp that is not NULL. | All types | Same as input type | +| LAST | Finds the value with the largest timestamp that is not NULL. | All types | Same as input type | +| STDDEV | Alias for STDDEV_SAMP, calculates the sample standard deviation. | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| STDDEV_POP | Calculates the population standard deviation. | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| STDDEV_SAMP | Calculates the sample standard deviation. | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| VARIANCE | Alias for VAR_SAMP, calculates the sample variance. | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| VAR_POP | Calculates the population variance. | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| VAR_SAMP | Calculates the sample variance. | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| EXTREME | Finds the value with the largest absolute value. If the largest absolute values of positive and negative values are equal, returns the positive value. | INT32 INT64 FLOAT DOUBLE | Same as input type | +| MODE | Finds the mode. Note: 1. There is a risk of memory exception when the number of distinct values in the input sequence is too large; 2. If all elements have the same frequency, i.e., there is no mode, a random element is returned; 3. If there are multiple modes, a random mode is returned; 4. NULL values are also counted in frequency, so even if not all values in the input sequence are NULL, the final result may still be NULL. | All types | Same as input type | +| MAX_BY | MAX_BY(x, y) finds the value of x corresponding to the maximum y in the binary input x and y. MAX_BY(time, x) returns the timestamp when x is at its maximum. | x and y can be of any type | Same as the data type of the first input x | +| MIN_BY | MIN_BY(x, y) finds the value of x corresponding to the minimum y in the binary input x and y. MIN_BY(time, x) returns the timestamp when x is at its minimum. | x and y can be of any type | Same as the data type of the first input x | +| FIRST_BY | FIRST_BY(x, y) finds the value of x in the same row when y is the first non-null value. | x and y can be of any type | Same as the data type of the first input x | +| LAST_BY | LAST_BY(x, y) finds the value of x in the same row when y is the last non-null value. | x and y can be of any type | Same as the data type of the first input x | + ### 2.3 Examples @@ -179,7 +208,29 @@ Total line number = 1 It costs 0.834s ``` -#### 2.3.3 First + +#### 2.3.3 Count_if + +Count `Non-Null` `arrival_time` Records in `table2` + +```sql +select count_if(arrival_time is not null) from table2; +``` + +The execution result is as follows: + +```sql ++-----+ +|_col0| ++-----+ +| 4| ++-----+ +Total line number = 1 +It costs 0.047s +``` + + +#### 2.3.4 First Finds the values with the smallest timestamp that are not NULL in the `temperature` and `humidity` columns. @@ -199,7 +250,7 @@ Total line number = 1 It costs 0.170s ``` -#### 2.3.4 Last +#### 2.3.5 Last Finds the values with the largest timestamp that are not NULL in the `temperature` and `humidity` columns. @@ -219,7 +270,7 @@ Total line number = 1 It costs 0.211s ``` -#### 2.3.5 First_by +#### 2.3.6 First_by Finds the `time` value of the row with the smallest timestamp that is not NULL in the `temperature` column, and the `humidity` value of the row with the smallest timestamp that is not NULL in the `temperature` column. @@ -239,7 +290,7 @@ Total line number = 1 It costs 0.269s ``` -#### 2.3.6 Last_by +#### 2.3.7 Last_by Queries the `time` value of the row with the largest timestamp that is not NULL in the `temperature` column, and the `humidity` value of the row with the largest timestamp that is not NULL in the `temperature` column. @@ -259,7 +310,7 @@ Total line number = 1 It costs 0.070s ``` -#### 2.3.7 Max_by +#### 2.3.8 Max_by Queries the `time` value of the row where the `temperature` column is at its maximum, and the `humidity` value of the row where the `temperature` column is at its maximum. @@ -279,7 +330,7 @@ Total line number = 1 It costs 0.172s ``` -#### 2.3.8 Min_by +#### 2.3.9 Min_by Queries the `time` value of the row where the `temperature` column is at its minimum, and the `humidity` value of the row where the `temperature` column is at its minimum. @@ -299,6 +350,7 @@ Total line number = 1 It costs 0.244s ``` + ## 3. Logical operators ### 3.1 Overview @@ -343,7 +395,7 @@ NULL OR true -- true ##### 3.2.2.1 Truth Table -The following truth table illustrates how `NULL` is handled in `AND` and `OR` operators: +The following truth table illustrates how `NULL` is handled in `AND` and `OR` operators: | a | b | a AND b | a OR b | | :---- | :---- | :------ | :----- | @@ -417,7 +469,7 @@ date_bin(interval,source,origin) 4. If `source` is `null`, the function returns `null`. 5. Mixing months and non-month time units (e.g., `1 MONTH 1 DAY`) is not supported due to ambiguity. -> For example, if the starting point is **April 30, 2000**, calculating `1 DAY` first and then `1 MONTH` results in **June 1, 2000**, whereas calculating `1 MONTH` first and then `1 DAY` results in **May 31, 2000**. The resulting dates are different. +> For example, if the starting point is **April 30, 2000**, calculating `1 DAY` first and then `1 MONTH` results in **June 1, 2000**, whereas calculating `1 MONTH` first and then `1 DAY` results in **May 31, 2000**. The resulting dates are different. #### 4.2.2 Examples @@ -635,31 +687,31 @@ It costs 0.319s ### 5.2 Mathematical functions -| Function Name | Description | Input | Output | Usage | -|:--------------|:-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|:----------------------------|:--------------------| :--------- | -| sin | Sine | double, float, INT64, INT32 | double | sin(x) | -| cos | Cosine | double, float, INT64, INT32 | double | cos(x) | -| tan | Tangent | double, float, INT64, INT32 | double | tan(x) | -| asin | Inverse Sine | double, float, INT64, INT32 | double | asin(x) | -| acos | Inverse Cosine | double, float, INT64, INT32 | double | acos(x) | -| atan | Inverse Tangent | double, float, INT64, INT32 | double | atan(x) | -| sinh | Hyperbolic Sine | double, float, INT64, INT32 | double | sinh(x) | -| cosh | Hyperbolic Cosine | double, float, INT64, INT32 | double | cosh(x) | -| tanh | Hyperbolic Tangent | double, float, INT64, INT32 | double | tanh(x) | -| degrees | Converts angle `x` in radians to degrees | double, float, INT64, INT32 | double | degrees(x) | -| radians | Radian Conversion from Degrees | double, float, INT64, INT32 | double | radians(x) | -| abs | Absolute Value | double, float, INT64, INT32 | Same as input type | abs(x) | -| sign | Returns the sign of `x`: - If `x = 0`, returns `0` - If `x > 0`, returns `1` - If `x < 0`, returns `-1` For `double/float` inputs: - If `x = NaN`, returns `NaN` - If `x = +Infinity`, returns `1.0` - If `x = -Infinity`, returns `-1.0` | double, float, INT64, INT32 | Same as input type | sign(x) | -| ceil | Rounds `x` up to the nearest integer | double, float, INT64, INT32 | double | ceil(x) | -| floor | Rounds `x` down to the nearest integer | double, float, INT64, INT32 | double | floor(x) | -| exp | Returns `e^x` (Euler's number raised to the power of `x`) | double, float, INT64, INT32 | double | exp(x) | -| ln | Returns the natural logarithm of `x` | double, float, INT64, INT32 | double | ln(x) | -| log10 | Returns the base 10 logarithm of `x` | double, float, INT64, INT32 | double | log10(x) | -| round | Rounds `x` to the nearest integer | double, float, INT64, INT32 | double | round(x) | -| round | Rounds `x` to `d` decimal places | double, float, INT64, INT32 | double | round(x, d)| -| sqrt | Returns the square root of `x`. | double, float, INT64, INT32 | double | sqrt(x) | -| e | Returns Euler’s number `e`. | | double | e() | -| pi | Pi (π) | | double | pi() | +| Function Name | Description | Input | Output | Usage | +|:--------------|:-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|:----------------------------|:-------------------| :--------- | +| sin | Sine | double, float, INT64, INT32 | double | sin(x) | +| cos | Cosine | double, float, INT64, INT32 | double | cos(x) | +| tan | Tangent | double, float, INT64, INT32 | double | tan(x) | +| asin | Inverse Sine | double, float, INT64, INT32 | double | asin(x) | +| acos | Inverse Cosine | double, float, INT64, INT32 | double | acos(x) | +| atan | Inverse Tangent | double, float, INT64, INT32 | double | atan(x) | +| sinh | Hyperbolic Sine | double, float, INT64, INT32 | double | sinh(x) | +| cosh | Hyperbolic Cosine | double, float, INT64, INT32 | double | cosh(x) | +| tanh | Hyperbolic Tangent | double, float, INT64, INT32 | double | tanh(x) | +| degrees | Converts angle `x` in radians to degrees | double, float, INT64, INT32 | double | degrees(x) | +| radians | Radian Conversion from Degrees | double, float, INT64, INT32 | double | radians(x) | +| abs | Absolute Value | double, float, INT64, INT32 | Same as input type | abs(x) | +| sign | Returns the sign of `x`: - If `x = 0`, returns `0` - If `x > 0`, returns `1` - If `x < 0`, returns `-1` For `double/float` inputs: - If `x = NaN`, returns `NaN` - If `x = +Infinity`, returns `1.0` - If `x = -Infinity`, returns `-1.0` | double, float, INT64, INT32 | Same as input type | sign(x) | +| ceil | Rounds `x` up to the nearest integer | double, float, INT64, INT32 | double | ceil(x) | +| floor | Rounds `x` down to the nearest integer | double, float, INT64, INT32 | double | floor(x) | +| exp | Returns `e^x` (Euler's number raised to the power of `x`) | double, float, INT64, INT32 | double | exp(x) | +| ln | Returns the natural logarithm of `x` | double, float, INT64, INT32 | double | ln(x) | +| log10 | Returns the base 10 logarithm of `x` | double, float, INT64, INT32 | double | log10(x) | +| round | Rounds `x` to the nearest integer | double, float, INT64, INT32 | double | round(x) | +| round | Rounds `x` to `d` decimal places | double, float, INT64, INT32 | double | round(x, d) | +| sqrt | Returns the square root of `x`. | double, float, INT64, INT32 | double | sqrt(x) | +| e | Returns Euler’s number `e`. | | double | e() | +| pi | Pi (π) | | double | pi() | ## 6. Conditional Expressions @@ -928,10 +980,10 @@ Msg: org.apache.iotdb.jdbc.IoTDBSQLException: 701: Invalid format string: %.5f ( ``` 3. Invalid Invocation Errors - Triggered if: +Triggered if: - * Total arguments < 2 (must include `pattern` and at least one argument).• - * `pattern` is not of type `STRING`/`TEXT`. +* Total arguments < 2 (must include `pattern` and at least one argument).• +* `pattern` is not of type `STRING`/`TEXT`. ```SQL -- Example 1 @@ -954,7 +1006,7 @@ The `||` operator is used for string concatenation and functions the same as the #### 8.1.2 LIKE Statement - The `LIKE` statement is used for pattern matching. For detailed usage, refer to Pattern Matching:[LIKE](#1-like-运算符). +The `LIKE` statement is used for pattern matching. For detailed usage, refer to Pattern Matching:[LIKE](#1-like-运算符). ### 8.2 String Functions @@ -1089,7 +1141,7 @@ SELECT regexp_like('1a 2b 14m', '\\d+b'); -- true - `\d+` means "one or more digits". - `b` represents the letter b. - In `'1a 2b 14m'`, the substring `'2b'` matches this pattern, so it returns `true`. - - + #### **Example 2: Matching the entire string** diff --git a/src/UserGuide/latest-Table/SQL-Manual/Basis-Function.md b/src/UserGuide/latest-Table/SQL-Manual/Basis-Function.md index 75734cc19..5c97d7435 100644 --- a/src/UserGuide/latest-Table/SQL-Manual/Basis-Function.md +++ b/src/UserGuide/latest-Table/SQL-Manual/Basis-Function.md @@ -119,6 +119,33 @@ Example 3: Query records where region is not 'Beijing' or 'Shanghai' SELECT * FROM table1 WHERE region NOT IN ('Beijing', 'Shanghai'); ``` +### 1.5 GREATEST and LEAST + +The `GREATEST` function returns the maximum value from a list of arguments, while the `LEAST` function returns the minimum value. The return type matches the input data type. + +Key Behaviors: +1. NULL Handling: Returns NULL if all arguments are NULL. +2. Parameter Requirements: Requires at least 2 arguments. +3. Type Constraints: All arguments must have the same data type. +4. Supported Types: `BOOLEAN`、`FLOAT`、`DOUBLE`、`INT32`、`INT64`、`STRING`、`TEXT`、`TIMESTAMP`、`DATE` + +**Syntax:** + +```sql + greatest(value1, value2, ..., valueN) + least(value1, value2, ..., valueN) +``` + +**Examples:** + +```sql +-- Retrieve the maximum value between `temperature` and `humidity` in `table2` +SELECT GREATEST(temperature,humidity) FROM table2; + +-- Retrieve the minimum value between `temperature` and `humidity` in `table2` +SELECT LEAST(temperature,humidity) FROM table2; +``` + ## 2. Aggregate functions ### 2.1 Overview @@ -129,27 +156,29 @@ SELECT * FROM table1 WHERE region NOT IN ('Beijing', 'Shanghai'); ### 2.2 Supported Aggregate Functions -| Function Name | Description | Allowed Input Types | Output Type | -| :------------ | :----------------------------------------------------------- | :------------------------- | :----------------------------------------- | -| COUNT | Counts the number of data points. | All types | INT64 | -| SUM | Calculates the sum. | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| AVG | Calculates the average. | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| MAX | Finds the maximum value. | All types | Same as input type | -| MIN | Finds the minimum value. | All types | Same as input type | -| FIRST | Finds the value with the smallest timestamp that is not NULL. | All types | Same as input type | -| LAST | Finds the value with the largest timestamp that is not NULL. | All types | Same as input type | -| STDDEV | Alias for STDDEV_SAMP, calculates the sample standard deviation. | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| STDDEV_POP | Calculates the population standard deviation. | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| STDDEV_SAMP | Calculates the sample standard deviation. | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| VARIANCE | Alias for VAR_SAMP, calculates the sample variance. | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| VAR_POP | Calculates the population variance. | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| VAR_SAMP | Calculates the sample variance. | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| EXTREME | Finds the value with the largest absolute value. If the largest absolute values of positive and negative values are equal, returns the positive value. | INT32 INT64 FLOAT DOUBLE | Same as input type | -| MODE | Finds the mode. Note: 1. There is a risk of memory exception when the number of distinct values in the input sequence is too large; 2. If all elements have the same frequency, i.e., there is no mode, a random element is returned; 3. If there are multiple modes, a random mode is returned; 4. NULL values are also counted in frequency, so even if not all values in the input sequence are NULL, the final result may still be NULL. | All types | Same as input type | -| MAX_BY | MAX_BY(x, y) finds the value of x corresponding to the maximum y in the binary input x and y. MAX_BY(time, x) returns the timestamp when x is at its maximum. | x and y can be of any type | Same as the data type of the first input x | -| MIN_BY | MIN_BY(x, y) finds the value of x corresponding to the minimum y in the binary input x and y. MIN_BY(time, x) returns the timestamp when x is at its minimum. | x and y can be of any type | Same as the data type of the first input x | -| FIRST_BY | FIRST_BY(x, y) finds the value of x in the same row when y is the first non-null value. | x and y can be of any type | Same as the data type of the first input x | -| LAST_BY | LAST_BY(x, y) finds the value of x in the same row when y is the last non-null value. | x and y can be of any type | Same as the data type of the first input x | +| Function Name | Description | Allowed Input Types | Output Type | +|:--------------|:---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|:-------------------------------------------------------------------|:-------------------------------------------| +| COUNT | Counts the number of data points. | All types | INT64 | +| COUNT_IF | COUNT_IF(exp) counts the number of rows that satisfy a specified boolean expression. | `exp` must be a boolean expression,(e.g. `count_if(temperature>20)`) | INT64 | +| SUM | Calculates the sum. | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| AVG | Calculates the average. | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| MAX | Finds the maximum value. | All types | Same as input type | +| MIN | Finds the minimum value. | All types | Same as input type | +| FIRST | Finds the value with the smallest timestamp that is not NULL. | All types | Same as input type | +| LAST | Finds the value with the largest timestamp that is not NULL. | All types | Same as input type | +| STDDEV | Alias for STDDEV_SAMP, calculates the sample standard deviation. | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| STDDEV_POP | Calculates the population standard deviation. | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| STDDEV_SAMP | Calculates the sample standard deviation. | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| VARIANCE | Alias for VAR_SAMP, calculates the sample variance. | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| VAR_POP | Calculates the population variance. | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| VAR_SAMP | Calculates the sample variance. | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| EXTREME | Finds the value with the largest absolute value. If the largest absolute values of positive and negative values are equal, returns the positive value. | INT32 INT64 FLOAT DOUBLE | Same as input type | +| MODE | Finds the mode. Note: 1. There is a risk of memory exception when the number of distinct values in the input sequence is too large; 2. If all elements have the same frequency, i.e., there is no mode, a random element is returned; 3. If there are multiple modes, a random mode is returned; 4. NULL values are also counted in frequency, so even if not all values in the input sequence are NULL, the final result may still be NULL. | All types | Same as input type | +| MAX_BY | MAX_BY(x, y) finds the value of x corresponding to the maximum y in the binary input x and y. MAX_BY(time, x) returns the timestamp when x is at its maximum. | x and y can be of any type | Same as the data type of the first input x | +| MIN_BY | MIN_BY(x, y) finds the value of x corresponding to the minimum y in the binary input x and y. MIN_BY(time, x) returns the timestamp when x is at its minimum. | x and y can be of any type | Same as the data type of the first input x | +| FIRST_BY | FIRST_BY(x, y) finds the value of x in the same row when y is the first non-null value. | x and y can be of any type | Same as the data type of the first input x | +| LAST_BY | LAST_BY(x, y) finds the value of x in the same row when y is the last non-null value. | x and y can be of any type | Same as the data type of the first input x | + ### 2.3 Examples @@ -179,7 +208,29 @@ Total line number = 1 It costs 0.834s ``` -#### 2.3.3 First + +#### 2.3.3 Count_if + +Count `Non-Null` `arrival_time` Records in `table2` + +```sql +select count_if(arrival_time is not null) from table2; +``` + +The execution result is as follows: + +```sql ++-----+ +|_col0| ++-----+ +| 4| ++-----+ +Total line number = 1 +It costs 0.047s +``` + + +#### 2.3.4 First Finds the values with the smallest timestamp that are not NULL in the `temperature` and `humidity` columns. @@ -199,7 +250,7 @@ Total line number = 1 It costs 0.170s ``` -#### 2.3.4 Last +#### 2.3.5 Last Finds the values with the largest timestamp that are not NULL in the `temperature` and `humidity` columns. @@ -219,7 +270,7 @@ Total line number = 1 It costs 0.211s ``` -#### 2.3.5 First_by +#### 2.3.6 First_by Finds the `time` value of the row with the smallest timestamp that is not NULL in the `temperature` column, and the `humidity` value of the row with the smallest timestamp that is not NULL in the `temperature` column. @@ -239,7 +290,7 @@ Total line number = 1 It costs 0.269s ``` -#### 2.3.6 Last_by +#### 2.3.7 Last_by Queries the `time` value of the row with the largest timestamp that is not NULL in the `temperature` column, and the `humidity` value of the row with the largest timestamp that is not NULL in the `temperature` column. @@ -259,7 +310,7 @@ Total line number = 1 It costs 0.070s ``` -#### 2.3.7 Max_by +#### 2.3.8 Max_by Queries the `time` value of the row where the `temperature` column is at its maximum, and the `humidity` value of the row where the `temperature` column is at its maximum. @@ -279,7 +330,7 @@ Total line number = 1 It costs 0.172s ``` -#### 2.3.8 Min_by +#### 2.3.9 Min_by Queries the `time` value of the row where the `temperature` column is at its minimum, and the `humidity` value of the row where the `temperature` column is at its minimum. @@ -299,6 +350,7 @@ Total line number = 1 It costs 0.244s ``` + ## 3. Logical operators ### 3.1 Overview @@ -1089,7 +1141,7 @@ SELECT regexp_like('1a 2b 14m', '\\d+b'); -- true - `\d+` means "one or more digits". - `b` represents the letter b. - In `'1a 2b 14m'`, the substring `'2b'` matches this pattern, so it returns `true`. - - + #### **Example 2: Matching the entire string** diff --git a/src/zh/UserGuide/Master/Table/SQL-Manual/Basis-Function.md b/src/zh/UserGuide/Master/Table/SQL-Manual/Basis-Function.md index de1f2fd14..62ad12638 100644 --- a/src/zh/UserGuide/Master/Table/SQL-Manual/Basis-Function.md +++ b/src/zh/UserGuide/Master/Table/SQL-Manual/Basis-Function.md @@ -120,6 +120,32 @@ SELECT * FROM table1 WHERE temperature IN (85.0, 90.0); SELECT * FROM table1 WHERE region NOT IN ('北京', '上海'); ``` +### 1.5 GREATEST 和 LEAST + +`Greatest` 函数用于返回参数列表中的最大值，`Least` 函数用于返回参数列表中的最小值，返回数据类型与输入类型相同。 +1. 空值处理：若所有参数均为 NULL，则返回 NULL。 +2. 参数要求：必须提供 至少 2 个参数。 +3. 类型约束：仅支持 相同数据类型 的参数比较。 +4. 支持类型： `BOOLEAN`、`FLOAT`、`DOUBLE`、`INT32`、`INT64`、`STRING`、`TEXT`、`TIMESTAMP`、`DATE` + +**语法：** + +```sql + greatest(value1, value2, ..., valueN) + least(value1, value2, ..., valueN) +``` + +**示例：** + +```sql +-- 查询 table2 中 temperature 和 humidity 的最大记录 +SELECT GREATEST(temperature,humidity) FROM table2; + +-- 查询 table2 中 temperature 和 humidity 的最小记录 +SELECT LEAST(temperature,humidity) FROM table2; +``` + + ## 2. 聚合函数 ### 2.1 概述 @@ -127,29 +153,31 @@ SELECT * FROM table1 WHERE region NOT IN ('北京', '上海'); 1. 聚合函数是多对一函数。它们对一组值进行聚合计算，得到单个聚合结果。 2. 除了 `COUNT()`之外，其他所有聚合函数都忽略空值，并在没有输入行或所有值为空时返回空值。 例如，`SUM()` 返回 null 而不是零，而 `AVG()` 在计数中不包括 null 值。 -### 2.2 支持的聚合函数 - -| 函数名 | 功能描述 | 允许的输入类型 | 输出类型 | -| ----------- | ------------------------------------------------------------ | ------------------------ | ----------------------------- | -| COUNT | 计算数据点数。 | 所有类型 | INT64 | -| SUM | 求和。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| AVG | 求平均值。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| MAX | 求最大值。 | 所有类型 | 与输入类型一致 | -| MIN | 求最小值。 | 所有类型 | 与输入类型一致 | -| FIRST | 求时间戳最小且不为 NULL 的值。 | 所有类型 | 与输入类型一致 | -| LAST | 求时间戳最大且不为 NULL 的值。 | 所有类型 | 与输入类型一致 | -| STDDEV | STDDEV_SAMP 的别名，求样本标准差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| STDDEV_POP | 求总体标准差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| STDDEV_SAMP | 求样本标准差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| VARIANCE | VAR_SAMP 的别名，求样本方差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| VAR_POP | 求总体方差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| VAR_SAMP | 求样本方差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| EXTREME | 求具有最大绝对值的值。如果正值和负值的最大绝对值相等，则返回正值。 | INT32 INT64 FLOAT DOUBLE | 与输入类型一致 | -| MODE | 求众数。注意： 1.输入序列的不同值个数过多时会有内存异常风险; 2.如果所有元素出现的频次相同，即没有众数，则随机返回一个元素; 3.如果有多个众数，则随机返回一个众数； 4. NULL 值也会被统计频次，所以即使输入序列的值不全为 NULL，最终结果也可能为 NULL。 | 所有类型 | 与输入类型一致 | -| MAX_BY | MAX_BY(x, y) 求二元输入 x 和 y 在 y 最大时对应的 x 的值。MAX_BY(time, x) 返回 x 取最大值时对应的时间戳。 | x 和 y 可以是任意类型 | 与第一个输入 x 的数据类型一致 | -| MIN_BY | MIN_BY(x, y) 求二元输入 x 和 y 在 y 最小时对应的 x 的值。MIN_BY(time, x) 返回 x 取最小值时对应的时间戳。 | x 和 y 可以是任意类型 | 与第一个输入 x 的数据类型一致 | -| FIRST_BY | FIRST_BY(x, y) 求当 y 为第一个不为 NULL 的值时，同一行里对应的 x 值。 | x 和 y 可以是任意类型 | 与第一个输入 x 的数据类型一致 | -| LAST_BY | LAST_BY(x, y) 求当 y 为最后一个不为 NULL 的值时，同一行里对应的 x 值。 | x 和 y 可以是任意类型 | 与第一个输入 x 的数据类型一致 | +### 2.2 支持的聚合函数 + +| 函数名 | 功能描述 | 允许的输入类型 | 输出类型 | +| ----------- | ------------------------------------------------------------ |-----------------------------------------------|------------------| +| COUNT | 计算数据点数。 | 所有类型 | INT64 | +| COUNT_IF | COUNT_IF(exp) 用于统计满足指定布尔表达式的记录行数 | exp 必须是一个布尔类型的表达式，例如 count_if(temperature>20) | INT64 | +| SUM | 求和。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| AVG | 求平均值。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| MAX | 求最大值。 | 所有类型 | 与输入类型一致 | +| MIN | 求最小值。 | 所有类型 | 与输入类型一致 | +| FIRST | 求时间戳最小且不为 NULL 的值。 | 所有类型 | 与输入类型一致 | +| LAST | 求时间戳最大且不为 NULL 的值。 | 所有类型 | 与输入类型一致 | +| STDDEV | STDDEV_SAMP 的别名，求样本标准差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| STDDEV_POP | 求总体标准差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| STDDEV_SAMP | 求样本标准差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| VARIANCE | VAR_SAMP 的别名，求样本方差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| VAR_POP | 求总体方差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| VAR_SAMP | 求样本方差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| EXTREME | 求具有最大绝对值的值。如果正值和负值的最大绝对值相等，则返回正值。 | INT32 INT64 FLOAT DOUBLE | 与输入类型一致 | +| MODE | 求众数。注意： 1.输入序列的不同值个数过多时会有内存异常风险; 2.如果所有元素出现的频次相同，即没有众数，则随机返回一个元素; 3.如果有多个众数，则随机返回一个众数； 4. NULL 值也会被统计频次，所以即使输入序列的值不全为 NULL，最终结果也可能为 NULL。 | 所有类型 | 与输入类型一致 | +| MAX_BY | MAX_BY(x, y) 求二元输入 x 和 y 在 y 最大时对应的 x 的值。MAX_BY(time, x) 返回 x 取最大值时对应的时间戳。 | x 和 y 可以是任意类型 | 与第一个输入 x 的数据类型一致 | +| MIN_BY | MIN_BY(x, y) 求二元输入 x 和 y 在 y 最小时对应的 x 的值。MIN_BY(time, x) 返回 x 取最小值时对应的时间戳。 | x 和 y 可以是任意类型 | 与第一个输入 x 的数据类型一致 | +| FIRST_BY | FIRST_BY(x, y) 求当 y 为第一个不为 NULL 的值时，同一行里对应的 x 值。 | x 和 y 可以是任意类型 | 与第一个输入 x 的数据类型一致 | +| LAST_BY | LAST_BY(x, y) 求当 y 为最后一个不为 NULL 的值时，同一行里对应的 x 值。 | x 和 y 可以是任意类型 | 与第一个输入 x 的数据类型一致 | + ### 2.3 示例 @@ -179,7 +207,29 @@ Total line number = 1 It costs 0.834s ``` -#### 2.3.3 First + +#### 2.3.3 Count_if + +统计 `table2` 中 到达时间 `arrival_time` 不是 `null` 的记录行数。 + +```sql +select count_if(arrival_time is not null) from table2; +``` + +执行结果如下： + +```sql ++-----+ +|_col0| ++-----+ +| 4| ++-----+ +Total line number = 1 +It costs 0.047s +``` + + +#### 2.3.4 First 查询`temperature`列、`humidity`列时间戳最小且不为 NULL 的值。 @@ -199,7 +249,7 @@ Total line number = 1 It costs 0.170s ``` -#### 2.3.4 Last +#### 2.3.5 Last 查询`temperature`列、`humidity`列时间戳最大且不为 NULL 的值。 @@ -219,7 +269,7 @@ Total line number = 1 It costs 0.211s ``` -#### 2.3.5 First_by +#### 2.3.6 First_by 查询 `temperature` 列中非 NULL 且时间戳最小的行的 `time` 值，以及 `temperature` 列中非 NULL 且时间戳最小的行的 `humidity` 值。 @@ -239,7 +289,7 @@ Total line number = 1 It costs 0.269s ``` -#### 2.3.6 Last_by +#### 2.3.7 Last_by 查询`temperature` 列中非 NULL 且时间戳最大的行的 `time` 值，以及 `temperature` 列中非 NULL 且时间戳最大的行的 `humidity` 值。 @@ -259,7 +309,7 @@ Total line number = 1 It costs 0.070s ``` -#### 2.3.7 Max_by +#### 2.3.8 Max_by 查询`temperature` 列中最大值所在行的 `time` 值，以及`temperature` 列中最大值所在行的 `humidity` 值。 @@ -279,7 +329,7 @@ Total line number = 1 It costs 0.172s ``` -#### 2.3.8 Min_by +#### 2.3.9 Min_by 查询`temperature` 列中最小值所在行的 `time` 值，以及`temperature` 列中最小值所在行的 `humidity` 值。 @@ -299,6 +349,8 @@ Total line number = 1 It costs 0.244s ``` + + ## 3. 逻辑运算符 ### 3.1 概述 @@ -636,31 +688,31 @@ It costs 0.319s ### 5.2 数学函数 -| 函数名 | 描述 | 输入 | 输出 | 用法 | -|-----------|------------------------------------------------------------------------------------------------------------------------------------------------------------| --------------------------- | ---------------------- | ---------- | -| sin | 正弦函数 | double、float、INT64、INT32 | double | sin(x) | -| cos | 余弦函数 | double、float、INT64、INT32 | double | cos(x) | -| tan | 正切函数 | double、float、INT64、INT32 | double | tan(x) | -| asin | 反正弦函数 | double、float、INT64、INT32 | double | asin(x) | -| acos | 反余弦函数 | double、float、INT64、INT32 | double | acos(x) | -| atan | 反正切函数 | double、float、INT64、INT32 | double | atan(x) | -| sinh | 双曲正弦函数 | double、float、INT64、INT32 | double | sinh(x) | -| cosh | 双曲余弦函数 | double、float、INT64、INT32 | double | cosh(x) | -| tanh | 双曲正切函数 | double、float、INT64、INT32 | double | tanh(x) | -| degrees | 将弧度角 x 转换为度 | double、float、INT64、INT32 | double | degrees(x) | -| radians | 将度转换为弧度 | double、float、INT64、INT32 | double | radians(x) | -| abs | 绝对值 | double、float、INT64、INT32 | 返回与输入类型相同的值 | abs(x) | -| sign | 返回 x 的符号函数，即：如果参数为 0，则返回 0，如果参数大于 0，则返回 1，如果参数小于 0，则返回 -1。对于 double/float 类型的参数，函数还会返回：如果参数为 NaN，则返回 NaN，如果参数为 +Infinity，则返回 1.0，如果参数为 -Infinity，则返回 -1.0。 | double、float、INT64、INT32 | 返回与输入类型相同的值 | sign(x) | -| ceil | 返回 x 向上取整到最近的整数。 | double、float、INT64、INT32 | double | ceil(x) | -| floor | 返回 x 向下取整到最近的整数。 | double、float、INT64、INT32 | double | floor(x) | -| exp | 返回欧拉数 e 的 x 次幂。 | double、float、INT64、INT32 | double | exp(x) | -| ln | 返回 x 的自然对数。 | double、float、INT64、INT32 | double | ln(x) | -| log10 | 返回 x 的以 10 为底的对数。 | double、float、INT64、INT32 | double | log10(x) | -| round | 返回 x 四舍五入到最近的整数。 | double、float、INT64、INT32 | double | round(x) | -| round | 返回 x 四舍五入到 d 位小数。 | double、float、INT64、INT32 | double | round(x, d) | -| sqrt | 返回 x 的平方根。 | double、float、INT64、INT32 | double | sqrt(x) | -| e | 自然指数 | | double | e() | -| pi | π | | double | pi() | +| 函数名 | 描述 | 输入 | 输出 | 用法 | +|-------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------| ---------------------- | ---------- | +| sin | 正弦函数 | double、float、INT64、INT32 | double | sin(x) | +| cos | 余弦函数 | double、float、INT64、INT32 | double | cos(x) | +| tan | 正切函数 | double、float、INT64、INT32 | double | tan(x) | +| asin | 反正弦函数 | double、float、INT64、INT32 | double | asin(x) | +| acos | 反余弦函数 | double、float、INT64、INT32 | double | acos(x) | +| atan | 反正切函数 | double、float、INT64、INT32 | double | atan(x) | +| sinh | 双曲正弦函数 | double、float、INT64、INT32 | double | sinh(x) | +| cosh | 双曲余弦函数 | double、float、INT64、INT32 | double | cosh(x) | +| tanh | 双曲正切函数 | double、float、INT64、INT32 | double | tanh(x) | +| degrees | 将弧度角 x 转换为度 | double、float、INT64、INT32 | double | degrees(x) | +| radians | 将度转换为弧度 | double、float、INT64、INT32 | double | radians(x) | +| abs | 绝对值 | double、float、INT64、INT32 | 返回与输入类型相同的值 | abs(x) | +| sign | 返回 x 的符号函数，即：如果参数为 0，则返回 0，如果参数大于 0，则返回 1，如果参数小于 0，则返回 -1。对于 double/float 类型的参数，函数还会返回：如果参数为 NaN，则返回 NaN，如果参数为 +Infinity，则返回 1.0，如果参数为 -Infinity，则返回 -1.0。 | double、float、INT64、INT32 | 返回与输入类型相同的值 | sign(x) | +| ceil | 返回 x 向上取整到最近的整数。 | double、float、INT64、INT32 | double | ceil(x) | +| floor | 返回 x 向下取整到最近的整数。 | double、float、INT64、INT32 | double | floor(x) | +| exp | 返回欧拉数 e 的 x 次幂。 | double、float、INT64、INT32 | double | exp(x) | +| ln | 返回 x 的自然对数。 | double、float、INT64、INT32 | double | ln(x) | +| log10 | 返回 x 的以 10 为底的对数。 | double、float、INT64、INT32 | double | log10(x) | +| round | 返回 x 四舍五入到最近的整数。 | double、float、INT64、INT32 | double | round(x) | +| round | 返回 x 四舍五入到 d 位小数。 | double、float、INT64、INT32 | double | round(x, d) | +| sqrt | 返回 x 的平方根。 | double、float、INT64、INT32 | double | sqrt(x) | +| e | 自然指数 | | double | e() | +| pi | π | | double | pi() | ## 6. 条件表达式 diff --git a/src/zh/UserGuide/latest-Table/SQL-Manual/Basis-Function.md b/src/zh/UserGuide/latest-Table/SQL-Manual/Basis-Function.md index 383c53dd4..00e421f38 100644 --- a/src/zh/UserGuide/latest-Table/SQL-Manual/Basis-Function.md +++ b/src/zh/UserGuide/latest-Table/SQL-Manual/Basis-Function.md @@ -120,6 +120,32 @@ SELECT * FROM table1 WHERE temperature IN (85.0, 90.0); SELECT * FROM table1 WHERE region NOT IN ('北京', '上海'); ``` +### 1.5 GREATEST 和 LEAST + +`Greatest` 函数用于返回参数列表中的最大值，`Least` 函数用于返回参数列表中的最小值，返回数据类型与输入类型相同。 +1. 空值处理：若所有参数均为 NULL，则返回 NULL。 +2. 参数要求：必须提供 至少 2 个参数。 +3. 类型约束：仅支持 相同数据类型 的参数比较。 +4. 支持类型： `BOOLEAN`、`FLOAT`、`DOUBLE`、`INT32`、`INT64`、`STRING`、`TEXT`、`TIMESTAMP`、`DATE` + +**语法：** + +```sql + greatest(value1, value2, ..., valueN) + least(value1, value2, ..., valueN) +``` + +**示例：** + +```sql +-- 查询 table2 中 temperature 和 humidity 的最大记录 +SELECT GREATEST(temperature,humidity) FROM table2; + +-- 查询 table2 中 temperature 和 humidity 的最小记录 +SELECT LEAST(temperature,humidity) FROM table2; +``` + + ## 2. 聚合函数 ### 2.1 概述 @@ -129,27 +155,29 @@ SELECT * FROM table1 WHERE region NOT IN ('北京', '上海'); ### 2.2 支持的聚合函数 -| 函数名 | 功能描述 | 允许的输入类型 | 输出类型 | -| ----------- | ------------------------------------------------------------ | ------------------------ | ----------------------------- | -| COUNT | 计算数据点数。 | 所有类型 | INT64 | -| SUM | 求和。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| AVG | 求平均值。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| MAX | 求最大值。 | 所有类型 | 与输入类型一致 | -| MIN | 求最小值。 | 所有类型 | 与输入类型一致 | -| FIRST | 求时间戳最小且不为 NULL 的值。 | 所有类型 | 与输入类型一致 | -| LAST | 求时间戳最大且不为 NULL 的值。 | 所有类型 | 与输入类型一致 | -| STDDEV | STDDEV_SAMP 的别名，求样本标准差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| STDDEV_POP | 求总体标准差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| STDDEV_SAMP | 求样本标准差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| VARIANCE | VAR_SAMP 的别名，求样本方差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| VAR_POP | 求总体方差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| VAR_SAMP | 求样本方差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | -| EXTREME | 求具有最大绝对值的值。如果正值和负值的最大绝对值相等，则返回正值。 | INT32 INT64 FLOAT DOUBLE | 与输入类型一致 | -| MODE | 求众数。注意： 1.输入序列的不同值个数过多时会有内存异常风险; 2.如果所有元素出现的频次相同，即没有众数，则随机返回一个元素; 3.如果有多个众数，则随机返回一个众数； 4. NULL 值也会被统计频次，所以即使输入序列的值不全为 NULL，最终结果也可能为 NULL。 | 所有类型 | 与输入类型一致 | -| MAX_BY | MAX_BY(x, y) 求二元输入 x 和 y 在 y 最大时对应的 x 的值。MAX_BY(time, x) 返回 x 取最大值时对应的时间戳。 | x 和 y 可以是任意类型 | 与第一个输入 x 的数据类型一致 | -| MIN_BY | MIN_BY(x, y) 求二元输入 x 和 y 在 y 最小时对应的 x 的值。MIN_BY(time, x) 返回 x 取最小值时对应的时间戳。 | x 和 y 可以是任意类型 | 与第一个输入 x 的数据类型一致 | -| FIRST_BY | FIRST_BY(x, y) 求当 y 为第一个不为 NULL 的值时，同一行里对应的 x 值。 | x 和 y 可以是任意类型 | 与第一个输入 x 的数据类型一致 | -| LAST_BY | LAST_BY(x, y) 求当 y 为最后一个不为 NULL 的值时，同一行里对应的 x 值。 | x 和 y 可以是任意类型 | 与第一个输入 x 的数据类型一致 | +| 函数名 | 功能描述 | 允许的输入类型 | 输出类型 | +| ----------- | ------------------------------------------------------------ |-----------------------------------------------|------------------| +| COUNT | 计算数据点数。 | 所有类型 | INT64 | +| COUNT_IF | COUNT_IF(exp) 用于统计满足指定布尔表达式的记录行数 | exp 必须是一个布尔类型的表达式，例如 count_if(temperature>20) | INT64 | +| SUM | 求和。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| AVG | 求平均值。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| MAX | 求最大值。 | 所有类型 | 与输入类型一致 | +| MIN | 求最小值。 | 所有类型 | 与输入类型一致 | +| FIRST | 求时间戳最小且不为 NULL 的值。 | 所有类型 | 与输入类型一致 | +| LAST | 求时间戳最大且不为 NULL 的值。 | 所有类型 | 与输入类型一致 | +| STDDEV | STDDEV_SAMP 的别名，求样本标准差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| STDDEV_POP | 求总体标准差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| STDDEV_SAMP | 求样本标准差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| VARIANCE | VAR_SAMP 的别名，求样本方差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| VAR_POP | 求总体方差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| VAR_SAMP | 求样本方差。 | INT32 INT64 FLOAT DOUBLE | DOUBLE | +| EXTREME | 求具有最大绝对值的值。如果正值和负值的最大绝对值相等，则返回正值。 | INT32 INT64 FLOAT DOUBLE | 与输入类型一致 | +| MODE | 求众数。注意： 1.输入序列的不同值个数过多时会有内存异常风险; 2.如果所有元素出现的频次相同，即没有众数，则随机返回一个元素; 3.如果有多个众数，则随机返回一个众数； 4. NULL 值也会被统计频次，所以即使输入序列的值不全为 NULL，最终结果也可能为 NULL。 | 所有类型 | 与输入类型一致 | +| MAX_BY | MAX_BY(x, y) 求二元输入 x 和 y 在 y 最大时对应的 x 的值。MAX_BY(time, x) 返回 x 取最大值时对应的时间戳。 | x 和 y 可以是任意类型 | 与第一个输入 x 的数据类型一致 | +| MIN_BY | MIN_BY(x, y) 求二元输入 x 和 y 在 y 最小时对应的 x 的值。MIN_BY(time, x) 返回 x 取最小值时对应的时间戳。 | x 和 y 可以是任意类型 | 与第一个输入 x 的数据类型一致 | +| FIRST_BY | FIRST_BY(x, y) 求当 y 为第一个不为 NULL 的值时，同一行里对应的 x 值。 | x 和 y 可以是任意类型 | 与第一个输入 x 的数据类型一致 | +| LAST_BY | LAST_BY(x, y) 求当 y 为最后一个不为 NULL 的值时，同一行里对应的 x 值。 | x 和 y 可以是任意类型 | 与第一个输入 x 的数据类型一致 | + ### 2.3 示例 @@ -179,7 +207,29 @@ Total line number = 1 It costs 0.834s ``` -#### 2.3.3 First + +#### 2.3.3 Count_if + +统计 `table2` 中 到达时间 `arrival_time` 不是 `null` 的记录行数。 + +```sql +select count_if(arrival_time is not null) from table2; +``` + +执行结果如下： + +```sql ++-----+ +|_col0| ++-----+ +| 4| ++-----+ +Total line number = 1 +It costs 0.047s +``` + + +#### 2.3.4 First 查询`temperature`列、`humidity`列时间戳最小且不为 NULL 的值。 @@ -199,7 +249,7 @@ Total line number = 1 It costs 0.170s ``` -#### 2.3.4 Last +#### 2.3.5 Last 查询`temperature`列、`humidity`列时间戳最大且不为 NULL 的值。 @@ -219,7 +269,7 @@ Total line number = 1 It costs 0.211s ``` -#### 2.3.5 First_by +#### 2.3.6 First_by 查询 `temperature` 列中非 NULL 且时间戳最小的行的 `time` 值，以及 `temperature` 列中非 NULL 且时间戳最小的行的 `humidity` 值。 @@ -239,7 +289,7 @@ Total line number = 1 It costs 0.269s ``` -#### 2.3.6 Last_by +#### 2.3.7 Last_by 查询`temperature` 列中非 NULL 且时间戳最大的行的 `time` 值，以及 `temperature` 列中非 NULL 且时间戳最大的行的 `humidity` 值。 @@ -259,7 +309,7 @@ Total line number = 1 It costs 0.070s ``` -#### 2.3.7 Max_by +#### 2.3.8 Max_by 查询`temperature` 列中最大值所在行的 `time` 值，以及`temperature` 列中最大值所在行的 `humidity` 值。 @@ -279,7 +329,7 @@ Total line number = 1 It costs 0.172s ``` -#### 2.3.8 Min_by +#### 2.3.9 Min_by 查询`temperature` 列中最小值所在行的 `time` 值，以及`temperature` 列中最小值所在行的 `humidity` 值。 @@ -299,6 +349,7 @@ Total line number = 1 It costs 0.244s ``` + ## 3. 逻辑运算符 ### 3.1 概述