ClickHouse/docs/en/sql-reference/functions/uuid-functions.md

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53	UUID

Functions for Working with UUID

The functions for working with UUID are listed below.

generateUUIDv4

Generates the UUID of version 4.

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.

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.

toUUID(String)

Returned value

The UUID type value.

Usage example

SELECT toUUID('61f0c404-5cb3-11e7-907b-a6006ad3dba0') AS uuid

┌─────────────────────────────────uuid─┐
│ 61f0c404-5cb3-11e7-907b-a6006ad3dba0 │
└──────────────────────────────────────┘

toUUIDOrNull (x)

It takes an argument of type String and tries to parse it into UUID. If failed, returns NULL.

toUUIDOrNull(String)

Returned value

The Nullable(UUID) type value.

Usage example

SELECT toUUIDOrNull('61f0c404-5cb3-11e7-907b-a6006ad3dba0T') AS uuid

┌─uuid─┐
│ ᴺᵁᴸᴸ │
└──────┘

toUUIDOrZero (x)

It takes an argument of type String and tries to parse it into UUID. If failed, returns zero UUID.

toUUIDOrZero(String)

Returned value

The UUID type value.

Usage example

SELECT toUUIDOrZero('61f0c404-5cb3-11e7-907b-a6006ad3dba0T') AS uuid

┌─────────────────────────────────uuid─┐
│ 00000000-0000-0000-0000-000000000000 │
└──────────────────────────────────────┘

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).

UUIDStringToNum(String)

Returned value

FixedString(16)

Usage examples

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) value, and returns a string containing 36 characters in text format.

UUIDNumToString(FixedString(16))

Returned value

String.

Usage example

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