mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-10-19 23:10:50 +00:00
23 lines
727 B
Markdown
23 lines
727 B
Markdown
<a name="special_data_type-nothing"></a>
|
|
|
|
# Nothing
|
|
|
|
The only purpose of this data type is to represent [NULL](../../query_language/syntax.md#null-literal), i.e., no value.
|
|
|
|
You can't create a `Nothing` type value, because it is used where a value is not expected. For example, `NULL` is written as `Nullable(Nothing)` ([Nullable](../../data_types/nullable.md#data_type-nullable) is the data type that allows storing `NULL` in tables).
|
|
|
|
The `Nothing` type is also used to denote empty arrays:
|
|
|
|
```bash
|
|
:) SELECT toTypeName(Array())
|
|
|
|
SELECT toTypeName([])
|
|
|
|
┌─toTypeName(array())─┐
|
|
│ Array(Nothing) │
|
|
└─────────────────────┘
|
|
|
|
1 rows in set. Elapsed: 0.062 sec.
|
|
```
|
|
|