--- 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', 'Europe/Moscow') 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`.