Question

我想在两列上分组。如果b不为空，我希望得到c组的总和，如果b为空，则希望得到a的组我写了这个查询，但是如果b为null则它不起作用！查询的结果是b不为空的所有行

...
export const routes: Routes = [
    {path:'', redirectTo:'/home', pathMatch:'full'},
    {path:'home', component: HomeComponent, canActivate: [AuthGuard]},
    {path:'login', component: LoginComponent },
    {path:'category', component:CategoryComponent, canActivate:[AuthGuard]},
    {path:'product', component:ProductComponent, canActivate:[AuthGuard]},
    {path:'**', redirectTo:''}
]
....

结果预期：

select  m.s.a ,
case when (m.l is not  null)  
then  m.l.code end , coalesce(sum(m.c),0  ) 
from material m where m.Item.id =:itemId 
group by m.s.a, case 
when (m.l is not null)  
then m.l.code end


+--+----+-------+---+
|  | s  | l     | c |
+--+----+-------+---+
|  |  a | d     |  1 |
|  |  a | d     |  9 |
|  |  a | e     |  3 |
|  |  a | f     |  4 |
|  |  c | g     |  5 |
|  |  c | g     |  6 |
|  |  c | h     | 20 |
|  |  d | null  |  7 |
|  |  d | null  |  8 |

Answer 1

默认情况下，oracle / postgres / mysql将生成预期的输出。

SELECT s,l,sum(c)
FROM temp
GROUP BY s,l;

如果您不想按NULL值分组，可以使用UNION

SELECT s,l,sum(c)
FROM temp
WHERE l is NOT NULL
GROUP BY s,l
UNION
SELECT s,l,sum(c)
FROM temp
WHERE l is NULL;

Answer 2

with data (col1, col2, val) as
(
  select 'a',   'd',        1 from dual union all  
  select 'a',   'd',        9 from dual union all  
  select 'a',   'e',        3 from dual union all  
  select 'a',   'f',        4 from dual union all  
  select 'c',   'g',        5 from dual union all  
  select 'c',   'g',        6 from dual union all  
  select 'c',   'h',       20 from dual union all  
  select 'd',   null,       7 from dual union all  
  select 'd',   null,       8 from dual union all
  select 'e',   'g',     null from dual  -- additional check if val is null
)
,
prs (col1, col2, col1n2) as 
(
  select distinct col1, col2, col1||'-'||col2 from data
)
,
rs (col, val) as 
(
  -- concatenate the columns that need to be grouped by 
  -- to act as one single column (col1 and col2)
  select col1||'-'||col2, sum(nvl(val,0)) from data group by col1||'-'||col2
)
select 
  prs.col1, prs.col2, rs.val 
from 
  rs join prs 
  on (prs.col1n2 = rs.col)
order by 1
;

按条件在hibernate中的两列进行分组

2 个答案: