从Oracle到MySQL的CASE语句

Question

我有以下查询，我需要从Oracle移植到MySQL。它执行时两者都没有任何编译错误，但结果表不同。在Oracle中，我获得每个计数列下的单个计数。但是在MySQL中，无论计数在哪里，它们都会降到a5以下。像这样：

在Oracle中：

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;

如何协调差异以使MySQL输出看起来像Oracle输出？谢谢你的帮助！

Answer 1

我使用datediff并且效果很好！