从Oracle到MySQL的CASE语句

Question

我有以下查询，需要从Oracle移植到MySQL。它在两者中都没有任何编译错误，但结果表是不同的。在Oracle中，每个计数列下都有个别计数。但在MySQL中，无论计数应该在哪里，它们都会在a5以下。像这样：

在Oracle：

但在MySQL：

select x1.alert_level, count(x1.a1), count(x1.a2), count(x1.a3), 
count(x1.a4), count(x1.a5) from 
(select 
table_name.column_name alias, 
case when (now() - column_name) <= 7 then 1 end as a1, 
case when (now() - column_name) between 7 and 30 then 1 end as a2, 
case when (now() - column_name) between 30 and 60 then 1 end as a3, 
case when (now() - column_name) between 60 and 90 then 1 end as a4, 
case when (now() - column_name) >= 90 then 1 end as a5 
FROM tables 
WHERE filter_conditions) x1 GROUP BY x1.alias; 

我如何可以调和的分歧，使MySQL的输出看起来像甲骨文输出？感谢您的帮助！

Answer 1

我用datediff它工作完美！