Question

我有一张如下表：

    ID   TYPE    VALUE
    1    CC 1     X
    1    CC 2     Y
    1    CC 3    NULL
    1    CC 4    NULL

我使用sql PIVOT和STUFF功能来获得所需的结果，但仍然无法做到。请有人帮我。

期望的结果：

ID [CC 1]  [CC 2]  [CC 3]  [CC 4]
1    X       Y      NULL    NULL

Answer 1

您可以通过多种方式解决此问题。我通常使用条件聚合：

ModelData *model = [ModelData MR_createEntity];
model.key = modelDataKey;
model.value = value;

[[NSManagedObjectContext MR_defaultContext] MR_saveToPersistentStoreWithCompletion:^(BOOL contextDidSave, NSError *error) {
    NSUInteger count = [ModelData MR_countOfEntities];
    if (count > 100) {
       //remove last element added
    }
}];

Answer 2

FULL OUTER JOIN的：

select coalesce(t1.id, t2.id, t3.id, t4.id),
       t1.value as cc1,
       t2.value as cc2,
       t3.value as cc3,
       t4.value as cc4
from (select id, value from tablename where type = 'CC 1') as t1
  full outer join (select id, value from tablename
                   where type = 'CC 2') as t2 ON t1.id = t2.id
  full outer join (select id, value from tablename
                   where type = 'CC 3') as t3 ON t2.id = t3.id
  full outer join (select id, value from tablename
                   where type = 'CC 4') as t  ON t3.id = t4.id

Answer 3

尝试以下方法：

Select id, listagg(value, '-')  within group(order by type) over (partition by id) as txt
From table group by Id, txt

Answer 4

以下是pivot的语法;

SELECT ID, [CC 1],[CC 2],[CC 3],[CC 4]
FROM yourtable
PIVOT
(min([value])  
FOR Type
in([CC 1],[CC 2],[CC 3],[CC 4])  
)AS p

在SQL中将多行组合成一行

4 个答案: