Question

我对案例陈述有点新，但下面是我的查询。

Table1
col1    col2    col3    col4    Month   Freeze
1   13  25  37  1   0
3   15  27  39  2   1
4   16  28  40  2   0
5   17  29  41  3   1
6   18  30  42  3   0
7   19  31  43  4   1
8   20  32  44  4   0
9   21  33  45  5   1
10  22  34  46  5   0
11  23  35  47  6   0

'我想要的结果'：

Select all records from Month1 to Month 12 where 'Freeze = 1' ,
if any month between 1 to 12 does not have Freeze = 1 then give me records for Freeze= 0 'just for the months which does not have 'Freeze = 1'

我最好的非工作尝试：

select * from tb1 where Month between 2 and 6 and freeze = 1 or Month in ('1' ,'2') and freeze = 0

Answer 1

以下是使用outer join的一个选项：

select t1.*
from Table1 t1
  left join Table1 t2 on 
    t1.month = t2.month and t2.freeze = 1
where t1.freeze = 1
    and t1.month between 1 and 12 
    or t2.month is null

SQL Fiddle Demo

结果：

COL1  COL2  COL3   COL4  MONTH  FREEZE
1     13      25   37    1      0
3     15      27   39    2      1
5     17      29   41    3      1
7     19      31   43    4      1
9     21      33   45    5      1
11    23      35   47    6      0

注意，根据您的数据，您可能需要使用此方法distinct。

Answer 2

以下是使用标准SQL的方法：

Select t1.*
from table1 t1
where Freeze = 1 and month between 1 and 12 or
      (not exists (select 1 from table where Freeze = 1 and month between 1 and 12) and
       month = 0
      );

使用窗口功能，你也可以这样做：

select t1.*
from (select t1.*,
             count(case when freeze = 1 and month between 1 and 2) over () as freeze1cnt
      from table1 t1
     ) t1
where month between 1 and 2 and freeze = 1 or
      month = 0 and freeze1cnt = 0;

where子句中的case语句？

2 个答案: