jdbc(datasource, schema, table) - Returns a table connected through a JDBC driver.
This table function requires a separate clickhouse-jdbc-bridge program to run.
It support projects nullable types (based on the DDL of the remote table being searched).
Example

SELECT * FROM jdbc('jdbc:mysql://localhost:3306/?user=root&password=root', 'schema', 'table')

SELECT * FROM jdbc('mysql://localhost:3306/?user=root&password=root', 'select * from schema.table')

SELECT * FROM jdbc('mysql-dev?p1=233', 'num Int32', 'select toInt32OrZero(''{{p1}}'') as num')

SELECT * 
FROM jdbc('mysql-dev?p1=233', 'num Int32', 'select toInt32OrZero(''{{p1}}'') as num')

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