[Feature request] Support multiple tables in FROM clause

[ivaigult]

The documentation suggests that only one table is supported in FROM clause:

[ FROM csv | spy | text | python_expression | json [ EXPLODE path ] ]

But it would be lovely to support multiple tables, like the full fat SQL does. This would allow to execute cross table queries, e.g.:

SELECT users.name, orders.details FROM users, orders WHERE users.id = orders.user_id;

[dcmoura]

Hey! Yes, this is true. Currently, we only support a single data source in the FROM clause. You can do very simple joins, but I understand it is not as convenient as having multiple sources.