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59 lines
1.9 KiB
Markdown
59 lines
1.9 KiB
Markdown
---
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toc_priority: 35
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toc_title: DATABASE
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---
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# CREATE DATABASE {#query-language-create-database}
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Creates a new database.
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``` sql
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CREATE DATABASE [IF NOT EXISTS] db_name [ON CLUSTER cluster] [ENGINE = engine(...)] [COMMENT 'Comment']
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```
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## Clauses {#clauses}
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### IF NOT EXISTS {#if-not-exists}
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If the `db_name` database already exists, then ClickHouse does not create a new database and:
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- Doesn’t throw an exception if clause is specified.
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- Throws an exception if clause isn’t specified.
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### ON CLUSTER {#on-cluster}
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ClickHouse creates the `db_name` database on all the servers of a specified cluster. More details in a [Distributed DDL](../../../sql-reference/distributed-ddl.md) article.
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### ENGINE {#engine}
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By default, ClickHouse uses its own [Atomic](../../../engines/database-engines/atomic.md) database engine. There are also [Lazy](../../../engines/database-engines/lazy.md), [MySQL](../../../engines/database-engines/mysql.md), [PostgresSQL](../../../engines/database-engines/postgresql.md), [MaterializedMySQL](../../../engines/database-engines/materialized-mysql.md), [MaterializedPostgreSQL](../../../engines/database-engines/materialized-postgresql.md), [Replicated](../../../engines/database-engines/replicated.md), [SQLite](../../../engines/database-engines/sqlite.md).
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### COMMENT {#comment}
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You can add a comment to the database when you creating it.
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The comment is supported for all database engines.
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**Syntax**
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``` sql
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CREATE DATABASE db_name ENGINE = engine(...) COMMENT 'Comment'
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```
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**Example**
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Query:
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``` sql
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CREATE DATABASE db_comment ENGINE = Memory COMMENT 'The temporary database';
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SELECT name, comment FROM system.databases WHERE name = 'db_comment';
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```
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Result:
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```text
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┌─name───────┬─comment────────────────┐
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│ db_comment │ The temporary database │
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└────────────┴────────────────────────┘
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```
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