比较来自不同表格的2列

Question

我有两张表，每列中有相同的列。让我们称它为颜色。我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;