table function support

[niyue]

Postgres supports table function (SQL server supports it as well), currently, the usage of table function is not supported. For some examples:

1. table function with table alias

SELECT 
  m.id
FROM
  my_func() m

• parser.columns is expected to return ['my_func.id'], but currently it returns ['m.id']
• parser.tables_aliases is expected to return {'m': 'my_func'}, but currently it returns {}

2. table function in parameterized statement

SELECT
  m.id
FROM 
  my_func(?) m

parser.tables is expected to return ['my_func'], but currently it returns ['?', 'my_func']

• References
  • postgres table function, https://www.postgresql.org/docs/7.3/xfunc-tablefunctions.html
  • SQL server table valued function, https://www.sqlservertutorial.net/sql-server-user-defined-functions/sql-server-table-valued-functions/