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---
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toc_priority: 3
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toc_title: JDBC
---
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# JDBC {#table-engine-jdbc}
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Allows ClickHouse to connect to external databases via [JDBC ](https://en.wikipedia.org/wiki/Java_Database_Connectivity ).
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To implement the JDBC connection, ClickHouse uses the separate program [clickhouse-jdbc-bridge ](https://github.com/ClickHouse/clickhouse-jdbc-bridge ) that should run as a daemon.
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This engine supports the [Nullable ](../../../sql-reference/data-types/nullable.md ) data type.
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## Creating a Table {#creating-a-table}
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``` sql
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CREATE TABLE [IF NOT EXISTS] [db.]table_name
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(
columns list...
)
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ENGINE = JDBC(datasource_uri, external_database, external_table)
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```
**Engine Parameters**
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- `datasource_uri` — URI or name of an external DBMS.
URI Format: `jdbc:<driver_name>://<host_name>:<port>/?user=<username>&password=<password>` .
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Example for MySQL: `jdbc:mysql://localhost:3306/?user=root&password=root` .
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- `external_database` — Database in an external DBMS.
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- `external_table` — Name of the table in `external_database` or a select query like `select * from table1 where column1=1` .
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## Usage Example {#usage-example}
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Creating a table in MySQL server by connecting directly with it’ s console client:
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``` text
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mysql> CREATE TABLE `test` .`test` (
-> `int_id` INT NOT NULL AUTO_INCREMENT,
-> `int_nullable` INT NULL DEFAULT NULL,
-> `float` FLOAT NOT NULL,
-> `float_nullable` FLOAT NULL DEFAULT NULL,
-> PRIMARY KEY (`int_id`));
Query OK, 0 rows affected (0,09 sec)
mysql> insert into test (`int_id`, `float` ) VALUES (1,2);
Query OK, 1 row affected (0,00 sec)
mysql> select * from test;
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+------+----------+-----+----------+
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| int_id | int_nullable | float | float_nullable |
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+------+----------+-----+----------+
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| 1 | NULL | 2 | NULL |
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+------+----------+-----+----------+
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1 row in set (0,00 sec)
```
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Creating a table in ClickHouse server and selecting data from it:
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``` sql
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CREATE TABLE jdbc_table
(
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`int_id` Int32,
`int_nullable` Nullable(Int32),
`float` Float32,
`float_nullable` Nullable(Float32)
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)
ENGINE JDBC('jdbc:mysql://localhost:3306/?user=root& password=root', 'test', 'test')
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```
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``` sql
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SELECT *
FROM jdbc_table
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```
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``` text
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┌─int_id─┬─int_nullable─┬─float─┬─float_nullable─┐
│ 1 │ ᴺᵁᴸᴸ │ 2 │ ᴺᵁᴸᴸ │
└────────┴──────────────┴───────┴────────────────┘
```
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``` sql
INSERT INTO jdbc_table(`int_id`, `float` )
SELECT toInt32(number), toFloat32(number * 1.0)
FROM system.numbers
```
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## See Also {#see-also}
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- [JDBC table function ](../../../sql-reference/table-functions/jdbc.md ).
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[Original article ](https://clickhouse.com/docs/en/engines/table-engines/integrations/jdbc/ ) <!--hide-->