sql面试 case /union all

1、sum（case when results='胜' then 1 else 0 end） as ‘胜’

要求查询出结果：

sql语句实现：

select date,
	sum(case when results='胜' then 1 else 0 end) AS '胜',
	sum(case when results='负' then 1 else 0 end) AS '负'
from game
group by date;

2、成绩分等级（case when 条件 then 结果 when 条件 then 结果 else 结果 end）

请写出生成如下图结果的sql语句( >=80 表示优秀， >=60 且 <80表示及格，<60表示不及格)？

效果图：

sql语句实现：

select
	(case when `语文` >= 80 then '优秀' when `语文` >= 60 then '及格' else '不及格' end) AS '语文',
	(case when `数学` >= 80 then '优秀' when `数学` >= 60 then '及格' else '不及格' end) AS '数学',
  (case when `英语` >= 80 then '优秀' when `英语` >= 60 then '及格' else '不及格' end) AS '英语'
from score

3、合并字段显示(union all)

合并显示按投资额度倒序排序，结果如下：

sql语句实现

select
	id AS '编号',
	'db_gain' AS '表名',
	'' as '连接',
	invest_money AS '投资额度',
	project_name as '项目名称',
	belongs_inductry as '产业领域',
	coperation as '合作方式'
from db_gain
UNION ALL
select
	id AS '编号',
	'achievement' as '表名',
	url as '连接',
	price as '投资额度',
	name as '项目名称',
	category as '产业领域',
	tradeType as '合作方式'
from achievement
order by `投资额度` desc;