Tool for sql query in multiple and different databases?

Does anyone know a simple SQL tool that allows me to do queries and joins through mutliple and different databases (oracle, sybase, syqlserver, ...) using JDBC / ODBC

Something like you what you do with Visual Foxpro

orclConn = SQLCONNECT({oracle database connection string})
SQLEXECUTE(orclConn, [SELECT ... FROM oracle_table], 'oracle_cursor')
fbConn = SQLCONNECT({firebird database connection string})
SQLEXECUTE(fblConn, [SELECT ... FROM firebird_table], 'firebird_cursor')
SELECT ... FROM oracle_cursor, firebird_cursor ON {join condition}

I need to do checks through different databases, such as "one client key available on another system"