原因别名在ORDER BY中有效，但在WHERE中无效

Question

我理解I can't reference an alias in the WHERE clause，但为什么会这样？是否有不同的解释？

这样的事情会产生错误：

declare @myTable table 
(
    num numeric(5,2),
    den numeric(5,2)
)
insert into @mytable 
select 1, 2
union
select 1, 3
union
select 2, 3
union
select 2, 4
union
select 2, 5
union
select null, 1

select num/den as 'calc' from @myTable
where calc is not null
order by calc

但这会返回行：

declare @myTable table 
(
    num numeric(5,2),
    den numeric(5,2)
)
insert into @mytable 
select 1, 2
union
select 1, 3
union
select 2, 3
union
select 2, 4
union
select 2, 5
union
select null, 1

select num/den as 'calc' from @myTable
--where calc is not null
order by calc

Answer 1

正如Cannot use Alias name in WHERE clause but can in ORDER BY中所述，由于自然查询处理顺序而导致：

1. @Configuration // @Import(Imprt.class) --> removed this public class Impl extends Abs {} @Configuration public abstract class Abs{ @Bean public ImportantBean importantBean(){ return new ImportantBean();} } @Configuration @Import(Impl.class) // ---> added new import here public class Imprt{ @Autowired private ImportantBean importantBean; }
2. FROM
3. ON
4. OUTER
5. WHERE
6. GROUP BY | CUBE
7. ROLLUP
8. HAVING
9. SELECT
10. DISTINCT
11. ORDER BY