如何使用列作为键来透视SQL中的列
我试图透视一个表并聚合一些子类别。但是,在聚合时,子类别没有正确连接 示例表如何使用列作为键来透视SQL中的列,sql,sql-server,pivot,string-aggregation,Sql,Sql Server,Pivot,String Aggregation,我试图透视一个表并聚合一些子类别。但是,在聚合时,子类别没有正确连接 示例表 | category | categorySub | |----------|-------------| | cat-1 | sub-1 | | cat-1 | sub-2 | | cat-1 | sub-3 | | cat-2 | sub-4 | | cat-2 | sub-5 | 实际产出 | category | cat
| category | categorySub |
|----------|-------------|
| cat-1 | sub-1 |
| cat-1 | sub-2 |
| cat-1 | sub-3 |
| cat-2 | sub-4 |
| cat-2 | sub-5 |
实际产出
| category | categorySub |
|----------|-------------------------------------------|
| cat-1 | ["sub-1","sub-2","sub-3","sub-4","sub-5"] |
| cat-2 | ["sub-1","sub-2","sub-3","sub-4","sub-5"] |
| category | categorySub |
|----------|---------------------------|
| cat-1 | ["sub-1","sub-2","sub-3"] |
| cat-2 | ["sub-4","sub-5"] |
所需输出
| category | categorySub |
|----------|-------------------------------------------|
| cat-1 | ["sub-1","sub-2","sub-3","sub-4","sub-5"] |
| cat-2 | ["sub-1","sub-2","sub-3","sub-4","sub-5"] |
| category | categorySub |
|----------|---------------------------|
| cat-1 | ["sub-1","sub-2","sub-3"] |
| cat-2 | ["sub-4","sub-5"] |
查询
select
[categoryMain] = [category],
[categorySub] = '["' + (select string_agg(categorySub, '","') from someTable where [categoryMain] = [category]) + '"]'
from someTable
group by [category]
如何引用[category]或其别名来减少字符串聚合?正如Martin所建议的,我们可以直接使用
string\u agg
,如下所示:
select
[categoryMain] = [category],
[categorySub] = '["' + (select string_agg(categorySub, '","') + '"]'
from someTable
group by [category]
您可以在
STRING\u AGG
本身中使用它
DECLARE @T Table(
cat Varchar(max),
SUB varchar(max))
Insert into @T Values ('cat-1','sub-1')
Insert into @T Values ('cat-1','sub-2')
Insert into @T Values ('cat-1','sub-3')
Insert into @T Values ('cat-2','sub-4')
Insert into @T Values ('cat-2','sub-5')
SELECT CAT AS CATEGORYMAIN, '["' + STRING_AGG(SUB, '","')+ '"]' AS SUB
FROM @T GROUP BY [CAT]
您不应该使用子查询。只需直接使用string_agg即可。谢谢您也不需要
select
,“[”+string\u agg(categorySub),““+”””,“+”””,
应该比select CAT作为CATEGORYMAIN,“[”+string\u agg(SUB),“)+“]”作为@t GROUP BY[CAT]的SUB更简单。