-- Add base_rate field to tbl_pack table
-- This stores the price without GST
-- prc field will store price with 18% GST

ALTER TABLE `tbl_pack` 
ADD COLUMN `base_rate` float NOT NULL DEFAULT '0' AFTER `prc`;

-- Update existing records to set base_rate equal to current prc (assuming current values are without GST)
UPDATE `tbl_pack` SET `base_rate` = `prc`;
