mysql - 帮助选择不同

Question

我有一个计划表:

tariff      |   monthly_cost
--------------------------
  Lion      ,    15.00
  Lion      ,    20.00
  Cat       ,    15.00
  Cat       ,    20.00
  Cat Extra ,    20.00
  Cat Extra ,    30.00

运行此 SQL 查询:

SELECT DISTINCT monthly_cost FROM plans;

这将是:

monthly_cost
------------
15.00
20.00
30.00

我希望结果如下所示:

tariff      |   monthly_cost
--------------------------
            ,    15.00
            ,    20.00
  Cat Extra ,    20.00
  Cat Extra ,    30.00

如何才能做到这一点？

Answer 1

select distinct null, monthly_cost
from plans
where tariff not like 'Cat Extra'
union
select tariff, monthly_cost
from plans
where tariff like 'Cat Extra'

肮脏，但高效。