PostgresSQL | Column Alter Error

Hey, I've setup most the columns and have added one-row using PG-Admin. I have now moved onto HeidiSQL. I've loaded up the table and changed the default value to 0 of both cash and bank (Int). I pressed save and received and error.

ALTER TABLE "maintable ALTER COLUMN "id" BIGINT NOT NULL;

This is the code that HeidiSQL generated. ^ This is the error it generated \/ ERROR: syntax error at or near "BIGINT" LINE 2: ALTER COLUMN "id" BIGINT NOT NULL

Please go to issue #595 and post the current wrong query which HeidiSQL fires, and how it should be fixed.