ข้อมูลมันออกมาไม่ตรงเงื่อนไขครับ WHERE tb_stock.code = tb_stock_code.code AND (select sum(tb_stock.stock_total) from tb_stock)

SELECT tb_stock.code, sum(tb_stock.add_to_stock) AS st_add, sum(tb_stock.stock_total) AS st_total, tb_stock_code.code_name
FROM tb_stock, tb_stock_code
WHERE tb_stock.code = tb_stock_code.code AND (select sum(tb_stock.stock_total) from tb_stock) < (select sum(tb_stock.add_to_stock) from tb_stock)
GROUP BY tb_stock.code