ClickHouse/docs/en/sql-reference/table-functions/jdbc.md
2024-03-18 11:37:21 +11:00

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---
slug: /en/sql-reference/table-functions/jdbc
sidebar_position: 100
sidebar_label: jdbc
---
# jdbc
:::note
clickhouse-jdbc-bridge contains experimental codes and is no longer supported. It may contain reliability issues and security vulnerabilities. Use it at your own risk.
ClickHouse recommend using built-in table functions in ClickHouse which provide a better alternative for ad-hoc querying scenarios (Postgres, MySQL, MongoDB, etc).
:::
`jdbc(datasource, schema, table)` - returns table that is connected via JDBC driver.
This table function requires separate [clickhouse-jdbc-bridge](https://github.com/ClickHouse/clickhouse-jdbc-bridge) program to be running.
It supports Nullable types (based on DDL of remote table that is queried).
**Examples**
``` sql
SELECT * FROM jdbc('jdbc:mysql://localhost:3306/?user=root&password=root', 'schema', 'table')
```
``` sql
SELECT * FROM jdbc('mysql://localhost:3306/?user=root&password=root', 'select * from schema.table')
```
``` sql
SELECT * FROM jdbc('mysql-dev?p1=233', 'num Int32', 'select toInt32OrZero(''{{p1}}'') as num')
```
``` sql
SELECT *
FROM jdbc('mysql-dev?p1=233', 'num Int32', 'select toInt32OrZero(''{{p1}}'') as num')
```
``` sql
SELECT a.datasource AS server1, b.datasource AS server2, b.name AS db
FROM jdbc('mysql-dev?datasource_column', 'show databases') a
INNER JOIN jdbc('self?datasource_column', 'show databases') b ON a.Database = b.name
```