ClickHouse/docs/en/query_language/functions/uuid_functions.md
ogorbacheva e275094f7d Added info about UUID to russian doc (#4314)
* Adding UUID to "ru" (drafts)

* fix russian text

* Adding UUID to "ru" (drafts)

* fix russian text

* fix english doc

* fixing links to nowhere
2019-02-09 00:37:56 +03:00

109 lines
3.1 KiB
Markdown

# Functions for working with UUID
The functions for working with UUID are listed below.
## generateUUIDv4 {#uuid_function-generate}
Generates the [UUID](../../data_types/uuid.md) of [version 4](https://tools.ietf.org/html/rfc4122#section-4.4).
```sql
generateUUIDv4()
```
**Returned value**
The UUID type value.
**Usage example**
This example demonstrates creating a table with the UUID type column and inserting a value into the table.
``` sql
:) CREATE TABLE t_uuid (x UUID) ENGINE=TinyLog
:) INSERT INTO t_uuid SELECT generateUUIDv4()
:) SELECT * FROM t_uuid
┌────────────────────────────────────x─┐
│ f4bf890f-f9dc-4332-ad5c-0c18e73f28e9 │
└──────────────────────────────────────┘
```
## toUUID (x)
Converts String type value to UUID type.
```sql
toUUID(String)
```
**Returned value**
The UUID type value.
**Usage example**
``` sql
:) SELECT toUUID('61f0c404-5cb3-11e7-907b-a6006ad3dba0') AS uuid
┌─────────────────────────────────uuid─┐
│ 61f0c404-5cb3-11e7-907b-a6006ad3dba0 │
└──────────────────────────────────────┘
```
## UUIDStringToNum
Accepts a string containing 36 characters in the format `xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx`, and returns it as a set of bytes in a [FixedString(16)](../../data_types/fixedstring.md).
``` sql
UUIDStringToNum(String)
```
**Returned value**
FixedString(16)
**Usage examples**
``` sql
:) SELECT
'612f3c40-5d3b-217e-707b-6a546a3d7b29' AS uuid,
UUIDStringToNum(uuid) AS bytes
┌─uuid─────────────────────────────────┬─bytes────────────┐
│ 612f3c40-5d3b-217e-707b-6a546a3d7b29 │ a/<@];!~p{jTj={) │
└──────────────────────────────────────┴──────────────────┘
```
## UUIDNumToString
Accepts a [FixedString(16)](../../data_types/fixedstring.md) value, and returns a string containing 36 characters in text format.
``` sql
UUIDNumToString(FixedString(16))
```
**Returned value**
String.
**Usage example**
``` sql
SELECT
'a/<@];!~p{jTj={)' AS bytes,
UUIDNumToString(toFixedString(bytes, 16)) AS uuid
┌─bytes────────────┬─uuid─────────────────────────────────┐
│ a/<@];!~p{jTj={) │ 612f3c40-5d3b-217e-707b-6a546a3d7b29 │
└──────────────────┴──────────────────────────────────────┘
```
## See also
- [dictGetUUID](ext_dict_functions.md)
- [dictGetUUIDOrDefault](ext_dict_functions#ext_dict_functions_dictGetTOrDefault)
[Original article](https://clickhouse.yandex/docs/en/query_language/functions/uuid_function/) <!--hide-->