[Feature] Extract JOIN information from queries

[galenseilis]

Hi sql-metadata developers!

I have just been playing around with the examples, and I love the idea of this package. Being able to extract meta-data about SQL queries can help information technology teams, software developers/engineers, analysts, and data scientists better understand how data architecture is being used.

One thing that seems to be missing is extracting relevant information about joins between tables.

My current thinking is there are usually these components:

• Type of join
• left table name
• right table name
• left sequence of columns joined on
• left sequence of columns joined on

A set of cases to watch out for are queries nested within a join. Some distinction should be drawn between tables vs subquery results.

Is this something you would be interested and willing to support?