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---
toc_priority: 37
toc_title: Operators
---
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# Operators {#operators}
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All operators are transformed to their corresponding functions at the query parsing stage in accordance with their precedence and associativity.
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Groups of operators are listed in order of priority (the higher it is in the list, the earlier the operator is connected to its arguments).
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## Access Operators {#access-operators}
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`a[N]` – Access to an element of an array. The `arrayElement(a, N)` function.
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`a.N` – Access to a tuple element. The `tupleElement(a, N)` function.
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## Numeric Negation Operator {#numeric-negation-operator}
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`-a` – The `negate (a)` function.
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## Multiplication and Division Operators {#multiplication-and-division-operators}
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`a * b` – The `multiply (a, b)` function.
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`a / b` – The `divide(a, b)` function.
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`a % b` – The `modulo(a, b)` function.
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## Addition and Subtraction Operators {#addition-and-subtraction-operators}
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`a + b` – The `plus(a, b)` function.
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`a - b` – The `minus(a, b)` function.
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## Comparison Operators {#comparison-operators}
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`a = b` – The `equals(a, b)` function.
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`a == b` – The `equals(a, b)` function.
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`a != b` – The `notEquals(a, b)` function.
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`a <> b` – The `notEquals(a, b)` function.
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`a <= b` – The `lessOrEquals(a, b)` function.
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`a >= b` – The `greaterOrEquals(a, b)` function.
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`a < b` – The `less(a, b)` function.
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`a > b` – The `greater(a, b)` function.
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`a LIKE s` – The `like(a, b)` function.
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`a NOT LIKE s` – The `notLike(a, b)` function.
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`a BETWEEN b AND c` – The same as `a >= b AND a <= c` .
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`a NOT BETWEEN b AND c` – The same as `a < b OR a > c` .
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## Operators for Working with Data Sets {#operators-for-working-with-data-sets}
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*See [IN operators ](statements/select.md#select-in-operators ).*
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`a IN ...` – The `in(a, b)` function.
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`a NOT IN ...` – The `notIn(a, b)` function.
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`a GLOBAL IN ...` – The `globalIn(a, b)` function.
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`a GLOBAL NOT IN ...` – The `globalNotIn(a, b)` function.
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## Operators for Working with Dates and Times {#operators-datetime}
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### EXTRACT {#operator-extract}
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``` sql
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EXTRACT(part FROM date);
```
Extracts a part 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:
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- `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.
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The `part` parameter is case-insensitive.
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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.
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Examples:
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``` sql
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SELECT EXTRACT(DAY FROM toDate('2017-06-15'));
SELECT EXTRACT(MONTH FROM toDate('2017-06-15'));
SELECT EXTRACT(YEAR FROM toDate('2017-06-15'));
```
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In the following example we create a table and insert into it a value with the `DateTime` type.
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``` sql
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CREATE TABLE test.Orders
(
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OrderId UInt64,
OrderName String,
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OrderDate DateTime
)
ENGINE = Log;
```
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``` sql
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INSERT INTO test.Orders VALUES (1, 'Jarlsberg Cheese', toDateTime('2008-10-11 13:23:44'));
```
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``` sql
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SELECT
toYear(OrderDate) AS OrderYear,
toMonth(OrderDate) AS OrderMonth,
toDayOfMonth(OrderDate) AS OrderDay,
toHour(OrderDate) AS OrderHour,
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toMinute(OrderDate) AS OrderMinute,
toSecond(OrderDate) AS OrderSecond
FROM test.Orders;
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```
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``` text
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┌─OrderYear─┬─OrderMonth─┬─OrderDay─┬─OrderHour─┬─OrderMinute─┬─OrderSecond─┐
│ 2008 │ 10 │ 11 │ 13 │ 23 │ 44 │
└───────────┴────────────┴──────────┴───────────┴─────────────┴─────────────┘
```
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You can see more examples in [tests ](https://github.com/ClickHouse/ClickHouse/blob/master/tests/queries/0_stateless/00619_extract.sql ).
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### INTERVAL {#operator-interval}
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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.
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Types of intervals:
- `SECOND`
- `MINUTE`
- `HOUR`
- `DAY`
- `WEEK`
- `MONTH`
- `QUARTER`
- `YEAR`
!!! warning "Warning"
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Intervals with different types can’ t be combined. You can’ t use expressions like `INTERVAL 4 DAY 1 HOUR` . Express intervals in units that are smaller or equal the the smallest unit of the interval, for example `INTERVAL 25 HOUR` . You can use consequtive operations like in the example below.
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Example:
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``` sql
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SELECT now() AS current_date_time, current_date_time + INTERVAL 4 DAY + INTERVAL 3 HOUR
```
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``` text
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┌───current_date_time─┬─plus(plus(now(), toIntervalDay(4)), toIntervalHour(3))─┐
│ 2019-10-23 11:16:28 │ 2019-10-27 14:16:28 │
└─────────────────────┴────────────────────────────────────────────────────────┘
```
**See Also**
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- [Interval ](../sql_reference/data_types/special_data_types/interval.md ) data type
- [toInterval ](../sql_reference/functions/type_conversion_functions.md#function-tointerval ) type convertion functions
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## Logical Negation Operator {#logical-negation-operator}
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`NOT a` – The `not(a)` function.
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## Logical AND Operator {#logical-and-operator}
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`a AND b` – The`and(a, b)` function.
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## Logical OR Operator {#logical-or-operator}
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`a OR b` – The `or(a, b)` function.
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## Conditional Operator {#conditional-operator}
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`a ? b : c` – The `if(a, b, c)` function.
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Note:
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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.
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## Conditional Expression {#operator_case}
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``` sql
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CASE [x]
WHEN a THEN b
[WHEN ... THEN ...]
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[ELSE c]
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END
```
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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` .
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## Concatenation Operator {#concatenation-operator}
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`s1 || s2` – The `concat(s1, s2) function.`
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## Lambda Creation Operator {#lambda-creation-operator}
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`x -> expr` – The `lambda(x, expr) function.`
The following operators do not have a priority, since they are brackets:
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## Array Creation Operator {#array-creation-operator}
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`[x1, ...]` – The `array(x1, ...) function.`
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## Tuple Creation Operator {#tuple-creation-operator}
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`(x1, x2, ...)` – The `tuple(x2, x2, ...) function.`
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## Associativity {#associativity}
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All binary operators have left associativity. For example, `1 + 2 + 3` is transformed to `plus(plus(1, 2), 3)` .
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Sometimes this doesn’ t work the way you expect. For example, `SELECT 4 > 2 > 3` will result in 0.
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For efficiency, the `and` and `or` functions accept any number of arguments. The corresponding chains of `AND` and `OR` operators are transformed to a single call of these functions.
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## Checking for `NULL` {#checking-for-null}
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ClickHouse supports the `IS NULL` and `IS NOT NULL` operators.
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### IS NULL {#operator-is-null}
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- For [Nullable ](../sql_reference/data_types/nullable.md ) type values, the `IS NULL` operator returns:
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- `1` , if the value is `NULL` .
- `0` otherwise.
- For other values, the `IS NULL` operator always returns `0` .
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<!-- -->
``` sql
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SELECT x+100 FROM t_null WHERE y IS NULL
```
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``` text
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┌─plus(x, 100)─┐
│ 101 │
└──────────────┘
```
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### IS NOT NULL {#is-not-null}
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- For [Nullable ](../sql_reference/data_types/nullable.md ) type values, the `IS NOT NULL` operator returns:
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- `0` , if the value is `NULL` .
- `1` otherwise.
- For other values, the `IS NOT NULL` operator always returns `1` .
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<!-- -->
``` sql
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SELECT * FROM t_null WHERE y IS NOT NULL
```
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``` text
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┌─x─┬─y─┐
│ 2 │ 3 │
└───┴───┘
```
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[Original article ](https://clickhouse.tech/docs/en/query_language/operators/ ) <!--hide-->