mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-10-21 16:00:50 +00:00
2d2bc052e1
* Typo fix. * Links fix. * Fixed links in docs. * More fixes. * docs/en: cleaning some files * docs/en: cleaning data_types * docs/en: cleaning database_engines * docs/en: cleaning development * docs/en: cleaning getting_started * docs/en: cleaning interfaces * docs/en: cleaning operations * docs/en: cleaning query_lamguage * docs/en: cleaning en * docs/ru: cleaning data_types * docs/ru: cleaning index * docs/ru: cleaning database_engines * docs/ru: cleaning development * docs/ru: cleaning general * docs/ru: cleaning getting_started * docs/ru: cleaning interfaces * docs/ru: cleaning operations * docs/ru: cleaning query_language * docs: cleaning interfaces/http * Update docs/en/data_types/array.md decorated ``` Co-Authored-By: BayoNet <da-daos@yandex.ru> * Update docs/en/getting_started/example_datasets/nyc_taxi.md fixed typo Co-Authored-By: BayoNet <da-daos@yandex.ru> * Update docs/en/getting_started/example_datasets/ontime.md fixed typo Co-Authored-By: BayoNet <da-daos@yandex.ru> * Update docs/en/interfaces/formats.md fixed error Co-Authored-By: BayoNet <da-daos@yandex.ru> * Update docs/en/operations/table_engines/custom_partitioning_key.md Co-Authored-By: BayoNet <da-daos@yandex.ru> * Update docs/en/operations/utils/clickhouse-local.md Co-Authored-By: BayoNet <da-daos@yandex.ru> * Update docs/en/query_language/dicts/external_dicts_dict_sources.md Co-Authored-By: BayoNet <da-daos@yandex.ru> * Update docs/en/operations/utils/clickhouse-local.md Co-Authored-By: BayoNet <da-daos@yandex.ru> * Update docs/en/query_language/functions/json_functions.md Co-Authored-By: BayoNet <da-daos@yandex.ru> * Update docs/en/query_language/functions/json_functions.md Co-Authored-By: BayoNet <da-daos@yandex.ru> * Update docs/en/query_language/functions/other_functions.md Co-Authored-By: BayoNet <da-daos@yandex.ru> * Update docs/en/query_language/functions/other_functions.md Co-Authored-By: BayoNet <da-daos@yandex.ru> * Update docs/en/query_language/functions/date_time_functions.md Co-Authored-By: BayoNet <da-daos@yandex.ru> * Update docs/en/operations/table_engines/jdbc.md Co-Authored-By: BayoNet <da-daos@yandex.ru> * docs: fixed error * docs: fixed error
70 lines
2.2 KiB
Markdown
70 lines
2.2 KiB
Markdown
# Array(T) {#data_type-array}
|
|
|
|
Array of `T`-type items.
|
|
|
|
`T` can be anything, including an array.
|
|
|
|
## Creating an array
|
|
|
|
You can use a function to create an array:
|
|
|
|
```sql
|
|
array(T)
|
|
```
|
|
|
|
You can also use square brackets.
|
|
|
|
```sql
|
|
[]
|
|
```
|
|
|
|
Example of creating an array:
|
|
|
|
```sql
|
|
SELECT array(1, 2) AS x, toTypeName(x)
|
|
```
|
|
```text
|
|
┌─x─────┬─toTypeName(array(1, 2))─┐
|
|
│ [1,2] │ Array(UInt8) │
|
|
└───────┴─────────────────────────┘
|
|
```
|
|
```sql
|
|
SELECT [1, 2] AS x, toTypeName(x)
|
|
```
|
|
```text
|
|
┌─x─────┬─toTypeName([1, 2])─┐
|
|
│ [1,2] │ Array(UInt8) │
|
|
└───────┴────────────────────┘
|
|
|
|
```
|
|
|
|
## Working with data types
|
|
|
|
When creating an array on the fly, ClickHouse automatically defines the argument type as the narrowest data type that can store all the listed arguments. If there are any [NULL](../query_language/syntax.md#null-literal) or [Nullable](nullable.md#data_type-nullable) type arguments, the type of array elements is [Nullable](nullable.md).
|
|
|
|
If ClickHouse couldn't determine the data type, it will generate an exception. For instance, this will happen when trying to create an array with strings and numbers simultaneously (`SELECT array(1, 'a')`).
|
|
|
|
Examples of automatic data type detection:
|
|
|
|
```sql
|
|
SELECT array(1, 2, NULL) AS x, toTypeName(x)
|
|
```
|
|
```text
|
|
┌─x──────────┬─toTypeName(array(1, 2, NULL))─┐
|
|
│ [1,2,NULL] │ Array(Nullable(UInt8)) │
|
|
└────────────┴───────────────────────────────┘
|
|
```
|
|
|
|
If you try to create an array of incompatible data types, ClickHouse throws an exception:
|
|
|
|
```sql
|
|
SELECT array(1, 'a')
|
|
```
|
|
```text
|
|
Received exception from server (version 1.1.54388):
|
|
Code: 386. DB::Exception: Received from localhost:9000, 127.0.0.1. DB::Exception: There is no supertype for types UInt8, String because some of them are String/FixedString and some of them are not.
|
|
```
|
|
|
|
|
|
[Original article](https://clickhouse.yandex/docs/en/data_types/array/) <!--hide-->
|