-- Remove deprecated flat columns from inv_product.
-- Must run AFTER 20260403_data_migration.sql has migrated existing rows.
-- Uses PREPARE/EXECUTE to skip each column that was already dropped
-- (MySQL has no DROP COLUMN IF EXISTS; that is a MariaDB-only extension).

SET @db = DATABASE();

SET @c = (SELECT COUNT(*) FROM information_schema.COLUMNS WHERE TABLE_SCHEMA=@db AND TABLE_NAME='inv_product' AND COLUMN_NAME='unit_pieces');
SET @s = IF(@c=1, 'ALTER TABLE `inv_product` DROP COLUMN `unit_pieces`', 'SELECT 1');
PREPARE stmt FROM @s; EXECUTE stmt; DEALLOCATE PREPARE stmt;

SET @c = (SELECT COUNT(*) FROM information_schema.COLUMNS WHERE TABLE_SCHEMA=@db AND TABLE_NAME='inv_product' AND COLUMN_NAME='unit_rolls');
SET @s = IF(@c=1, 'ALTER TABLE `inv_product` DROP COLUMN `unit_rolls`', 'SELECT 1');
PREPARE stmt FROM @s; EXECUTE stmt; DEALLOCATE PREPARE stmt;

SET @c = (SELECT COUNT(*) FROM information_schema.COLUMNS WHERE TABLE_SCHEMA=@db AND TABLE_NAME='inv_product' AND COLUMN_NAME='stock_quantity');
SET @s = IF(@c=1, 'ALTER TABLE `inv_product` DROP COLUMN `stock_quantity`', 'SELECT 1');
PREPARE stmt FROM @s; EXECUTE stmt; DEALLOCATE PREPARE stmt;

SET @c = (SELECT COUNT(*) FROM information_schema.COLUMNS WHERE TABLE_SCHEMA=@db AND TABLE_NAME='inv_product' AND COLUMN_NAME='location');
SET @s = IF(@c=1, 'ALTER TABLE `inv_product` DROP COLUMN `location`', 'SELECT 1');
PREPARE stmt FROM @s; EXECUTE stmt; DEALLOCATE PREPARE stmt;

SET @c = (SELECT COUNT(*) FROM information_schema.COLUMNS WHERE TABLE_SCHEMA=@db AND TABLE_NAME='inv_product' AND COLUMN_NAME='cost_price');
SET @s = IF(@c=1, 'ALTER TABLE `inv_product` DROP COLUMN `cost_price`', 'SELECT 1');
PREPARE stmt FROM @s; EXECUTE stmt; DEALLOCATE PREPARE stmt;