UUID 函数

请注意:
下文中的一些示例引用自 ClickHouse 社区文档 并经过一定修改确保可以在 ByteHouse 中正常使用。

generateUUIDv4

Generates the UUID of version 4 .

Syntax

generateUUIDv4()

Returned value

• The UUID type value.

Examples
This example demonstrates creating a table with the UUID type column and inserting a value into the table.

CREATE TABLE test.functionGenerateUUIDv4 (x UUID) ENGINE=CnchMergeTree ORDER BY x;
INSERT INTO test.functionGenerateUUIDv4 SELECT generateUUIDv4();
SELECT * FROM test.functionGenerateUUIDv4;

┌─x────────────────────────────────────┐
│ a630fbcb-1a32-4902-b5cc-dd51eba8cf4b │
└──────────────────────────────────────┘

toUUID

Converts String type value to UUID type. Exception will be raised if input string is invalid uuid format.

Syntax

toUUID(String)

Arguments

• String — string in uuid format.

Returned value

• The UUID type value.

Examples

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

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

toUUIDOrNull

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

Syntax

toUUIDOrNull(String)

Arguments

• String — string in uuid format.

Returned value

• The Nullable(UUID) type value.

Examples

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

┌─uuid─┐
│ ᴺᵁᴸᴸ │
└──────┘

toUUIDOrZero

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

Syntax

toUUIDOrZero(String)

Arguments

• String — string in uuid format.

Returned value

• The UUID type value.

Examples

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

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

generateUUIDv4

Generates the UUID of version 4 .

Syntax

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

Syntax

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

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

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 │

└──────────────────────────────────────┘