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