比较来自不同表的2列

Question

我有2个表，每个表都有相同的列。让我们称之为颜色。如何比较两者以显示表B中不在表A中的独特颜色？

Answer 1

select b.color
  from tbl1 b
 where not exists (select * from tbl2 a where b.color=a.color)

Answer 2

SELECT b.color AS color FROM tableB b
LEFT JOIN tableA a ON a.color = b.color
WHERE a.color IS NULL;