change sql from my sql to postgres

The code below is work for mysql but not work on postgresql
How can I change it   plese help

ERROR:  column t.open does not exist
LINE 12: join helpertable h on  t.Open - t.Low-h.value >= 0  
                                ^

SELECT
t.Date,
t.name,
t.Open,
t.Low,
t.dif,
t.sellprice,
h.value,t.sellprice-t.open+h.value as profitc, (t.sellprice-t.open+h.value )*2 as profitt,
(t.sellprice-t.open+h.value )*2 *100*t.multi/t.open as percentProfittMul
FROM
sename t
join helpertable h on  t.Open - t.Low-h.value >= 0