Last updated：2020-12-28 14:56:18

KLog supports basic SELECT queries in the following syntax:

```
select_expr [, select_expr] ...
[WHERE where_condition]
[GROUP BY {col_name | expr}, ... ]
[ORDER BY {col_name | expr} [ASC | DESC], ...]
[LIMIT [offset,] row_count]
```

Note: For more information about the limits on SQL queries, see Limits.

Operator | Description |
---|---|

< | Less than |

> | Greater than |

<= | Less than or equal to |

>= | Greater than or equal to |

= | Equal to |

<> | Not equal to |

!= | Not equal to |

BETWEEN | Determines whether a value is within a specified range. |

IS NULL/IS NOT NULL | Determines whether a value is NULL. |

Operator | Description |
---|---|

AND | The result is true if both values are true. |

OR | The result is true if either value is true. |

NOT | The result is true if the value is false. |

Operator or function | Description |
---|---|

+ | Adds two values. |

- | Subtracts one value from another. |

* | Multiplies two values. |

/ | Divides one value by another to obtain a quotient. |

% | Divides one value by another to obtain a remainder. |

abs(x) | Returns the absolute value of x. |

cbrt(x) | Returns the cube root of x. |

ceiling(x) | Returns x rounded up to the nearest integer. |

e() | Returns Euler’s number. |

exp(x) | Returns Euler’s number raised to the power of x. |

expm1(x) | Returns exp(x) - 1. |

floor(x) | Returns x rounded down to the nearest integer. |

log10(x) | Returns the logarithm of x to base 10. |

round(x) | Returns x rounded to the nearest integer. |

sqrt(x) | Returns the square root of x. |

radians(x) | Converts angle x in degrees to radians. |

acos(x) | Returns the arc cosine of x. |

asin(x) | Returns the arc sine of x. |

atan(x) | Returns the arc tangent of x. |

atan2(y,x) | Returns the arc tangent of y/x. |

cos(x) | Returns the cosine of x. |

sin(x) | Returns the sine of x. |

sinh(x) | Returns the hyperbolic sine of x |

cosh(x) | Returns the hyperbolic cosine of x. |

tan(x) | Returns the tangent of x. |

Function | Description |
---|---|

current_date() | Returns the current date. |

current_time() | Returns the current time. |

current_timestamp(date) | Returns the current timestamp. |

date_diff(expr,datetime1,datetime2) | Returns the time difference in the specified unit between timestamp1 and timestamp2. |

date_diff(expr,n,date) | Returns the date and time after the time in the specified unit is added to the date. |

datetime_format(datetime,expr) | Returns the date and time in the format specified by expr. |

datetime_parse(datetime,expr) | Converts the date and time to the specified format. |

time_parse(time,expr) | Converts the time to the specified format. |

date_part(datetime,expr) | Extracts the specified part from the date and time. |

date_trunc(datetime,expr) | Sets the fields that are less than the specified value to zero in the date and time. |

day_of_month(datetime) | Extracts the day of the month from the date and time. |

day_of_week(datetime) | Extracts the day of the week from the date and time. |

day_of_year(datetime) | Extracts the day of the year from the date and time. |

day_name(datetime) | Extracts the day of the week from the date and time. |

hour_of_day(datetime) | Extracts the hour of the day from the date and time. |

ios_day_of_week(datetime) | Extracts the day of the week from the date and time. |

ios_week_of_year(datetime) | Extracts the week of the year from the date and time. |

minute_of_day(datetime) | Extracts the minute of the day from the date and time. |

minute_of_hour(datetime) | Extracts the minute of the hour from the date and time. |

month_of_year(datetime) | Extracts the month of the year from the date and time. |

month_name(datetime) | Extracts the name of the month from the date and time. |

now() | Returns the current timestamp. |

second_of_minute(datetime) | Extracts the second of the minute from the date and time. |

quarter(datetime) | Extracts the quarter from the date and time. |

today() | Returns the current date. |

week_of_year(datetime) | Extracts the week of the year from the date and time. |

year(datetime) | Extracts the year from the date and time. |

extract(datetime_function from datetime) | Extracts fields from the date and time by using the specified date and time function. |

Function | Description |
---|---|

avg(x) | Returns the arithmetic average of x values. |

count(*) | Returns the number of rows. |

count(distinct x) | Returns the number of rows that have unique non-null x values. |

count(all x) | Returns the number of rows that have non-null x values. |

first(a,b) | Returns the first a value after data is sorted by b in the ascending order. |

last(a,b) | Returns the last a value after data is sorted by b in the ascending order. |

max(x) | Returns the maximum value. |

min(x) | Returns the minimum value. |

sum(x) | Returns the sum of x values. |

Function | Description |
---|---|

kurtosis(x) | Returns the distribution of x values. |

mad(x) | Returns the variability of x values. |

kurtosis(x) | Returns the distribution of x values. |

percentile(x) | Returns the nth percentile of x values. |

percentile_rank(x) | Returns the distribution of x values. |

skewness(x) | Returns the skewness of x. |

stddev_pop(x) | Returns the population standard deviation of x. |

stddev_samp(x) | Returns the sample standard deviation of x. |

sum_of_squares(x) | Returns the sum of squares of x. |

var_pop(x) | Returns the population variance of x. |

var_samp(x) | Returns the sample variance of x. |

Function | Description |
---|---|

histogram(x,interval) | Returns all matching values based on the specified interval. |

Function | Description |
---|---|

cast(x as data_type) | Converts x to the specified data type. |

Convert(x,data_type) | Converts x to the specified data type. |

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