mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-14 10:22:10 +00:00
377 lines
13 KiB
Markdown
377 lines
13 KiB
Markdown
---
|
||
toc_priority: 38
|
||
toc_title: Operators
|
||
---
|
||
|
||
# Operators {#operators}
|
||
|
||
ClickHouse transforms operators to their corresponding functions at the query parsing stage according to their priority, precedence, and associativity.
|
||
|
||
## Access Operators {#access-operators}
|
||
|
||
`a[N]` – Access to an element of an array. The `arrayElement(a, N)` function.
|
||
|
||
`a.N` – Access to a tuple element. The `tupleElement(a, N)` function.
|
||
|
||
## Numeric Negation Operator {#numeric-negation-operator}
|
||
|
||
`-a` – The `negate (a)` function.
|
||
|
||
For tuple negation: [tupleNegate](../../sql-reference/functions/tuple-functions.md#tuplenegate).
|
||
|
||
## Multiplication and Division Operators {#multiplication-and-division-operators}
|
||
|
||
`a * b` – The `multiply (a, b)` function.
|
||
|
||
For multiplying tuple by number: [tupleMultiplyByNumber](../../sql-reference/functions/tuple-functions.md#tuplemultiplybynumber), for scalar profuct: [dotProduct](../../sql-reference/functions/tuple-functions.md#dotproduct).
|
||
|
||
`a / b` – The `divide(a, b)` function.
|
||
|
||
For dividing tuple by number: [tupleDivideByNumber](../../sql-reference/functions/tuple-functions.md#tupledividebynumber).
|
||
|
||
`a % b` – The `modulo(a, b)` function.
|
||
|
||
## Addition and Subtraction Operators {#addition-and-subtraction-operators}
|
||
|
||
`a + b` – The `plus(a, b)` function.
|
||
|
||
For tuple addiction: [tuplePlus](../../sql-reference/functions/tuple-functions.md#tupleplus).
|
||
|
||
`a - b` – The `minus(a, b)` function.
|
||
|
||
For tuple subtraction: [tupleMinus](../../sql-reference/functions/tuple-functions.md#tupleminus).
|
||
|
||
## Comparison Operators {#comparison-operators}
|
||
|
||
`a = b` – The `equals(a, b)` function.
|
||
|
||
`a == b` – The `equals(a, b)` function.
|
||
|
||
`a != b` – The `notEquals(a, b)` function.
|
||
|
||
`a <> b` – The `notEquals(a, b)` function.
|
||
|
||
`a <= b` – The `lessOrEquals(a, b)` function.
|
||
|
||
`a >= b` – The `greaterOrEquals(a, b)` function.
|
||
|
||
`a < b` – The `less(a, b)` function.
|
||
|
||
`a > b` – The `greater(a, b)` function.
|
||
|
||
`a LIKE s` – The `like(a, b)` function.
|
||
|
||
`a NOT LIKE s` – The `notLike(a, b)` function.
|
||
|
||
`a ILIKE s` – The `ilike(a, b)` function.
|
||
|
||
`a BETWEEN b AND c` – The same as `a >= b AND a <= c`.
|
||
|
||
`a NOT BETWEEN b AND c` – The same as `a < b OR a > c`.
|
||
|
||
## Operators for Working with Data Sets {#operators-for-working-with-data-sets}
|
||
|
||
See [IN operators](../../sql-reference/operators/in.md) and [EXISTS](../../sql-reference/operators/exists.md) operator.
|
||
|
||
`a IN ...` – The `in(a, b)` function.
|
||
|
||
`a NOT IN ...` – The `notIn(a, b)` function.
|
||
|
||
`a GLOBAL IN ...` – The `globalIn(a, b)` function.
|
||
|
||
`a GLOBAL NOT IN ...` – The `globalNotIn(a, b)` function.
|
||
|
||
`a = ANY (subquery)` – The `in(a, subquery)` function.
|
||
|
||
`a != ANY (subquery)` – The same as `a NOT IN (SELECT singleValueOrNull(*) FROM subquery)`.
|
||
|
||
`a = ALL (subquery)` – The same as `a IN (SELECT singleValueOrNull(*) FROM subquery)`.
|
||
|
||
`a != ALL (subquery)` – The `notIn(a, subquery)` function.
|
||
|
||
|
||
**Examples**
|
||
|
||
Query with ALL:
|
||
|
||
``` sql
|
||
SELECT number AS a FROM numbers(10) WHERE a > ALL (SELECT number FROM numbers(3, 3));
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─a─┐
|
||
│ 6 │
|
||
│ 7 │
|
||
│ 8 │
|
||
│ 9 │
|
||
└───┘
|
||
```
|
||
|
||
Query with ANY:
|
||
|
||
``` sql
|
||
SELECT number AS a FROM numbers(10) WHERE a > ANY (SELECT number FROM numbers(3, 3));
|
||
```
|
||
|
||
Result:
|
||
|
||
``` text
|
||
┌─a─┐
|
||
│ 4 │
|
||
│ 5 │
|
||
│ 6 │
|
||
│ 7 │
|
||
│ 8 │
|
||
│ 9 │
|
||
└───┘
|
||
```
|
||
|
||
## Operators for Working with Dates and Times {#operators-datetime}
|
||
|
||
### EXTRACT {#operator-extract}
|
||
|
||
``` sql
|
||
EXTRACT(part FROM date);
|
||
```
|
||
|
||
Extract parts from a given date. For example, you can retrieve a month from a given date, or a second from a time.
|
||
|
||
The `part` parameter specifies which part of the date to retrieve. The following values are available:
|
||
|
||
- `DAY` — The day of the month. Possible values: 1–31.
|
||
- `MONTH` — The number of a month. Possible values: 1–12.
|
||
- `YEAR` — The year.
|
||
- `SECOND` — The second. Possible values: 0–59.
|
||
- `MINUTE` — The minute. Possible values: 0–59.
|
||
- `HOUR` — The hour. Possible values: 0–23.
|
||
|
||
The `part` parameter is case-insensitive.
|
||
|
||
The `date` parameter specifies the date or the time to process. Either [Date](../../sql-reference/data-types/date.md) or [DateTime](../../sql-reference/data-types/datetime.md) type is supported.
|
||
|
||
Examples:
|
||
|
||
``` sql
|
||
SELECT EXTRACT(DAY FROM toDate('2017-06-15'));
|
||
SELECT EXTRACT(MONTH FROM toDate('2017-06-15'));
|
||
SELECT EXTRACT(YEAR FROM toDate('2017-06-15'));
|
||
```
|
||
|
||
In the following example we create a table and insert into it a value with the `DateTime` type.
|
||
|
||
``` sql
|
||
CREATE TABLE test.Orders
|
||
(
|
||
OrderId UInt64,
|
||
OrderName String,
|
||
OrderDate DateTime
|
||
)
|
||
ENGINE = Log;
|
||
```
|
||
|
||
``` sql
|
||
INSERT INTO test.Orders VALUES (1, 'Jarlsberg Cheese', toDateTime('2008-10-11 13:23:44'));
|
||
```
|
||
|
||
``` sql
|
||
SELECT
|
||
toYear(OrderDate) AS OrderYear,
|
||
toMonth(OrderDate) AS OrderMonth,
|
||
toDayOfMonth(OrderDate) AS OrderDay,
|
||
toHour(OrderDate) AS OrderHour,
|
||
toMinute(OrderDate) AS OrderMinute,
|
||
toSecond(OrderDate) AS OrderSecond
|
||
FROM test.Orders;
|
||
```
|
||
|
||
``` text
|
||
┌─OrderYear─┬─OrderMonth─┬─OrderDay─┬─OrderHour─┬─OrderMinute─┬─OrderSecond─┐
|
||
│ 2008 │ 10 │ 11 │ 13 │ 23 │ 44 │
|
||
└───────────┴────────────┴──────────┴───────────┴─────────────┴─────────────┘
|
||
```
|
||
|
||
You can see more examples in [tests](https://github.com/ClickHouse/ClickHouse/blob/master/tests/queries/0_stateless/00619_extract.sql).
|
||
|
||
### INTERVAL {#operator-interval}
|
||
|
||
Creates an [Interval](../../sql-reference/data-types/special-data-types/interval.md)-type value that should be used in arithmetical operations with [Date](../../sql-reference/data-types/date.md) and [DateTime](../../sql-reference/data-types/datetime.md)-type values.
|
||
|
||
Types of intervals:
|
||
- `SECOND`
|
||
- `MINUTE`
|
||
- `HOUR`
|
||
- `DAY`
|
||
- `WEEK`
|
||
- `MONTH`
|
||
- `QUARTER`
|
||
- `YEAR`
|
||
|
||
You can also use a string literal when setting the `INTERVAL` value. For example, `INTERVAL 1 HOUR` is identical to the `INTERVAL '1 hour'` or `INTERVAL '1' hour`.
|
||
|
||
!!! warning "Warning"
|
||
Intervals with different types can’t be combined. You can’t use expressions like `INTERVAL 4 DAY 1 HOUR`. Specify intervals in units that are smaller or equal to the smallest unit of the interval, for example, `INTERVAL 25 HOUR`. You can use consecutive operations, like in the example below.
|
||
|
||
Examples:
|
||
|
||
``` sql
|
||
SELECT now() AS current_date_time, current_date_time + INTERVAL 4 DAY + INTERVAL 3 HOUR;
|
||
```
|
||
|
||
``` text
|
||
┌───current_date_time─┬─plus(plus(now(), toIntervalDay(4)), toIntervalHour(3))─┐
|
||
│ 2020-11-03 22:09:50 │ 2020-11-08 01:09:50 │
|
||
└─────────────────────┴────────────────────────────────────────────────────────┘
|
||
```
|
||
|
||
``` sql
|
||
SELECT now() AS current_date_time, current_date_time + INTERVAL '4 day' + INTERVAL '3 hour';
|
||
```
|
||
|
||
``` text
|
||
┌───current_date_time─┬─plus(plus(now(), toIntervalDay(4)), toIntervalHour(3))─┐
|
||
│ 2020-11-03 22:12:10 │ 2020-11-08 01:12:10 │
|
||
└─────────────────────┴────────────────────────────────────────────────────────┘
|
||
```
|
||
|
||
``` sql
|
||
SELECT now() AS current_date_time, current_date_time + INTERVAL '4' day + INTERVAL '3' hour;
|
||
```
|
||
|
||
``` text
|
||
┌───current_date_time─┬─plus(plus(now(), toIntervalDay('4')), toIntervalHour('3'))─┐
|
||
│ 2020-11-03 22:33:19 │ 2020-11-08 01:33:19 │
|
||
└─────────────────────┴────────────────────────────────────────────────────────────┘
|
||
```
|
||
|
||
You can work with dates without using `INTERVAL`, just by adding or subtracting seconds, minutes, and hours. For example, an interval of one day can be set by adding `60*60*24`.
|
||
|
||
!!! note "Note"
|
||
The `INTERVAL` syntax or `addDays` function are always preferred. Simple addition or subtraction (syntax like `now() + ...`) doesn't consider time settings. For example, daylight saving time.
|
||
|
||
|
||
Examples:
|
||
|
||
``` sql
|
||
SELECT toDateTime('2014-10-26 00:00:00', 'Asia/Istanbul') AS time, time + 60 * 60 * 24 AS time_plus_24_hours, time + toIntervalDay(1) AS time_plus_1_day;
|
||
```
|
||
|
||
``` text
|
||
┌────────────────time─┬──time_plus_24_hours─┬─────time_plus_1_day─┐
|
||
│ 2014-10-26 00:00:00 │ 2014-10-26 23:00:00 │ 2014-10-27 00:00:00 │
|
||
└─────────────────────┴─────────────────────┴─────────────────────┘
|
||
```
|
||
|
||
**See Also**
|
||
|
||
- [Interval](../../sql-reference/data-types/special-data-types/interval.md) data type
|
||
- [toInterval](../../sql-reference/functions/type-conversion-functions.md#function-tointerval) type conversion functions
|
||
|
||
## Logical AND Operator {#logical-and-operator}
|
||
|
||
Syntax `SELECT a AND b` — calculates logical conjunction of `a` and `b` with the function [and](../../sql-reference/functions/logical-functions.md#logical-and-function).
|
||
|
||
## Logical OR Operator {#logical-or-operator}
|
||
|
||
Syntax `SELECT a OR b` — calculates logical disjunction of `a` and `b` with the function [or](../../sql-reference/functions/logical-functions.md#logical-or-function).
|
||
|
||
## Logical Negation Operator {#logical-negation-operator}
|
||
|
||
Syntax `SELECT NOT a` — calculates logical negation of `a` with the function [not](../../sql-reference/functions/logical-functions.md#logical-not-function).
|
||
|
||
## Conditional Operator {#conditional-operator}
|
||
|
||
`a ? b : c` – The `if(a, b, c)` function.
|
||
|
||
Note:
|
||
|
||
The conditional operator calculates the values of b and c, then checks whether condition a is met, and then returns the corresponding value. If `b` or `C` is an [arrayJoin()](../../sql-reference/functions/array-join.md#functions_arrayjoin) function, each row will be replicated regardless of the “a” condition.
|
||
|
||
## Conditional Expression {#operator_case}
|
||
|
||
``` sql
|
||
CASE [x]
|
||
WHEN a THEN b
|
||
[WHEN ... THEN ...]
|
||
[ELSE c]
|
||
END
|
||
```
|
||
|
||
If `x` is specified, then `transform(x, [a, ...], [b, ...], c)` function is used. Otherwise – `multiIf(a, b, ..., c)`.
|
||
|
||
If there is no `ELSE c` clause in the expression, the default value is `NULL`.
|
||
|
||
The `transform` function does not work with `NULL`.
|
||
|
||
## Concatenation Operator {#concatenation-operator}
|
||
|
||
`s1 || s2` – The `concat(s1, s2) function.`
|
||
|
||
## Lambda Creation Operator {#lambda-creation-operator}
|
||
|
||
`x -> expr` – The `lambda(x, expr) function.`
|
||
|
||
The following operators do not have a priority since they are brackets:
|
||
|
||
## Array Creation Operator {#array-creation-operator}
|
||
|
||
`[x1, ...]` – The `array(x1, ...) function.`
|
||
|
||
## Tuple Creation Operator {#tuple-creation-operator}
|
||
|
||
`(x1, x2, ...)` – The `tuple(x2, x2, ...) function.`
|
||
|
||
## Associativity {#associativity}
|
||
|
||
All binary operators have left associativity. For example, `1 + 2 + 3` is transformed to `plus(plus(1, 2), 3)`.
|
||
Sometimes this does not work the way you expect. For example, `SELECT 4 > 2 > 3` will result in 0.
|
||
|
||
For efficiency, the `and` and `or` functions accept any number of arguments. The corresponding chains of `AND` and `OR` operators are transformed into a single call of these functions.
|
||
|
||
## Checking for `NULL` {#checking-for-null}
|
||
|
||
ClickHouse supports the `IS NULL` and `IS NOT NULL` operators.
|
||
|
||
### IS NULL {#operator-is-null}
|
||
|
||
- For [Nullable](../../sql-reference/data-types/nullable.md) type values, the `IS NULL` operator returns:
|
||
- `1`, if the value is `NULL`.
|
||
- `0` otherwise.
|
||
- For other values, the `IS NULL` operator always returns `0`.
|
||
|
||
Can be optimized by enabling the [optimize_functions_to_subcolumns](../../operations/settings/settings.md#optimize-functions-to-subcolumns) setting. With `optimize_functions_to_subcolumns = 1` the function reads only [null](../../sql-reference/data-types/nullable.md#finding-null) subcolumn instead of reading and processing the whole column data. The query `SELECT n IS NULL FROM table` transforms to `SELECT n.null FROM TABLE`.
|
||
|
||
<!-- -->
|
||
|
||
``` sql
|
||
SELECT x+100 FROM t_null WHERE y IS NULL
|
||
```
|
||
|
||
``` text
|
||
┌─plus(x, 100)─┐
|
||
│ 101 │
|
||
└──────────────┘
|
||
```
|
||
|
||
### IS NOT NULL {#is-not-null}
|
||
|
||
- For [Nullable](../../sql-reference/data-types/nullable.md) type values, the `IS NOT NULL` operator returns:
|
||
- `0`, if the value is `NULL`.
|
||
- `1` otherwise.
|
||
- For other values, the `IS NOT NULL` operator always returns `1`.
|
||
|
||
<!-- -->
|
||
|
||
``` sql
|
||
SELECT * FROM t_null WHERE y IS NOT NULL
|
||
```
|
||
|
||
``` text
|
||
┌─x─┬─y─┐
|
||
│ 2 │ 3 │
|
||
└───┴───┘
|
||
```
|
||
|
||
Can be optimized by enabling the [optimize_functions_to_subcolumns](../../operations/settings/settings.md#optimize-functions-to-subcolumns) setting. With `optimize_functions_to_subcolumns = 1` the function reads only [null](../../sql-reference/data-types/nullable.md#finding-null) subcolumn instead of reading and processing the whole column data. The query `SELECT n IS NOT NULL FROM table` transforms to `SELECT NOT n.null FROM TABLE`.
|