SQL Select，是否可以基于键将特定的重复行合并为1？

Question

I'm a little stumped on this. I have a table that looks like the following:

Group_Key      Trigger_Type        Event_Type         Result_Id
1                   A                   A                 1
2                   B                   B                 2
3                   C                   C                 3 
3                   C                   C                 4
4                   E                   E                 5
5                   F                   F                 6
5                   F                   F                 7

There are rows that will have the same survey (all columns should be the same aside from result_id) key but they will have a different result_Id. Is it possible to do a select on the table that grabs the rows and instead of returning 2 rows because of the result_id, it groups those ones that have dupes into a single row with the result_id being a concatenated string? So for instance, return this:

Group_Key      Trigger_Type        Event_Type         Result_Id
1                   A                   A                 1
2                   B                   B                 2
3                   C                   C                 3,4 
4                   E                   E                 5
5                   F                   F                 6,7

Is this possible?

Thank you,

Answer 1

Here's an example using a recursive CTE to replicate the functionality of string_agg() . This example is from the upsert scripts for execsql , and was written by Elizabeth Shea. It will have to be modified for your particular use, substituting your own column names for the execsql variable references.

if object_id('tempdb..#agg_string') is not null drop table #agg_string;
with enum as 
    (
    select
        cast(!!#string_col!! as varchar(max)) as agg_string,
        row_number() over (order by !!#order_col!!) as row_num
    from
        !!#table_name!!
    ),
agg as 
    (
    select
        one.agg_string,
        one.row_num
    from
        enum as one
    where
        one.row_num=1
    UNION ALL
    select
        agg.agg_string + '!!#delimiter!!' + enum.agg_string as agg_string,
        enum.row_num
    from 
        agg, enum
    where
        enum.row_num=agg.row_num+1
    )
select
agg_string 
into #agg_string
from agg
where row_num=(select max(row_num) from agg);

Answer 2

Using Gordon Linoff's hint you can GROUP BY the values that should be the same and concatenate the other values in one row using STRING_AGG :

SELECT Group_Key, Trigger_Type, Event_Type, STRING_AGG(Result_Id, ',') as ResultId
FROM myTable
GROUP BY Group_Key, Trigger_Type, Event_Type

Answer 3

I would add the ordering of values to MicSim's solutions as follows:

select Group_Key, Trigger_Type, Event_Type,
string_agg(Result_Id, ',') within group (order by Result_Id)
from survey
group by Group_Key, Trigger_Type, Event_Type

Answer 4

MS-SQL Server will not recognise STRING_AGG function. Try stuff() as shown below:

SELECT Group_Key ,Trigger_Type, Event_Type,   
STUFF(
    (SELECT CONCAT( Result_Id , ', ') AS [text()]
    FROM [dbo].[TestTable] t2  
    WHERE t1.Group_Key = t2.Group_Key
    AND t1.Trigger_Type = t2.Trigger_Type
    AND t1.Event_Type= t2.Event_Type
    ORDER BY Group_Key ,Trigger_Type, Event_Type
    FOR XML PATH('')), 1, 0, '') AS Result_Id 
FROM [dbo].[TestTable] t1 

GROUP BY Group_Key ,Trigger_Type, Event_Type

Hope this helps.