学步园

示例一

SELECT 学号, 姓名,
 等级=
    CASE
    WHEN 总学分 IS NULL THEN ‘尚未选课’
       WHEN 总学分 < 50 THEN ‘不及格’
        WHEN 总学分 >=50 and 总学分<=52 THEN ‘合格’
        ELSE ‘优秀’
    END  FROM  XS    WHERE 专业名=’计算机’

示例二

update employee
set e_wage =
 case
  when job_level = ’1’ then e_wage*1.08
  when job_level = ’2’ then e_wage*1.07
  when job_level = ’3’ then e_wage*1.06
  else e_wage*1.05
 end

示例三

select a, (case a when 1 then '中' else '国' end) AS B  from table1

示例四

case(
  select count(*) from (select jx0502.isdel from jx0502 ) row_ where 1=1 ---查询出总数结果
)
when 1 then '不开课'  ---总数结果为1时显示 '不开课'
……
……
……
else '开课' end ---否则显示 '开课'