Feature: support position column in common sql query

[sundy-li]

Summary

Description for this feature.

this should work

 select $1, $2 from (select 1,2,3);

CREATE OR REPLACE TABLE monthly_sales(empid INT, amount INT, month TEXT);
INSERT INTO monthly_sales VALUES
    (1, 10000, 'JAN'),
    (1, 400, 'JAN'),
    (2, 4500, 'JAN'),
    (2, 35000, 'JAN'),
    (1, 5000, 'FEB'),
    (1, 3000, 'FEB'),
    (2, 200, 'FEB'),
    (2, 90500, 'FEB'),
    (1, 6000, 'MAR'),
    (1, 5000, 'MAR'),
    (2, 2500, 'MAR'),
    (2, 9500, 'MAR'),
    (1, 8000, 'APR'),
    (1, 10000, 'APR'),
    (2, 800, 'APR'),
    (2, 4500, 'APR');
 


    SELECT $1, $2, $3 
    FROM monthly_sales
        PIVOT(SUM(amount) FOR MONTH IN (SELECT DISTINCT month FROM monthly_sales))
    ORDER BY EMPID