select id,price, [0-5]= case when price between 0 and 5 then price end, [6-10]= case when price between 6 and 10 then price end, [11-20]= case when price between 11 and 20 then price end from tb
select id,price, (case when price between 0 and 5 then price end) as 0-5, (case when price between 6 and 10 then price end) 6-10, (case when price between 11 and 20 then price end)11-20 from tb
select id,price, (case when price between 0 and 5 then price end) as 0-5, (case when price between 6 and 10 then price end) as 6-10, (case when price between 11 and 20 then price end) as 11-20 from tb
这样会不会 price=4 的时候 (case when price between 6 and 10 then price end) as 6-10, (case when price between 11 and 20 then price end) as 11-20 也执行一次 能不能用嵌套 减少判断次数 当然不能觉得减少 执行 =4 是 不执行后面的两句 =7 时不执行 后面的一句 提高一点效率 (不知sql查询优化器会不会考虑这些)
[0-5]= case when price between 0 and 5 then price end,
[6-10]= case when price between 6 and 10 then price end,
[11-20]= case when price between 11 and 20 then price end
from tb
select id,price,
(case when price between 0 and 5 then price end) as 0-5,
(case when price between 6 and 10 then price end) 6-10,
(case when price between 11 and 20 then price end)11-20
from tb
(case when price between 0 and 5 then price end) as 0-5,
(case when price between 6 and 10 then price end) as 6-10,
(case when price between 11 and 20 then price end) as 11-20
from tb
(case when price between 11 and 20 then price end) as 11-20
也执行一次 能不能用嵌套 减少判断次数
当然不能觉得减少
执行 =4 是 不执行后面的两句
=7 时不执行 后面的一句
提高一点效率
(不知sql查询优化器会不会考虑这些)