How can I "merge", "flatten" or "pivot" results from a query which returns multiple rows into a single result?

Question

I have a simple query over a table, which returns results like the following:

id    id_type  id_ref
2702  5        31
2702  16       14
2702  17       3
2702  40       1
2703  23       4
2703  23       5
2703  34       6
2704  1        14

And I would like to merge the results into a single row, for instance:

id    concatenation 
2702  5,16,17,40:31,14,3,1
2703  23,23,34:4,5,6
2704  1:14

Is there any way to do this within a trigger?

NB: I know I can use a cursor, but I would really prefer not to unless there is no better way.

The database is Sybase version 12.5.4.

Answer 1

Since it's rather difficult to get this done in Sybase using a select statement I would suggest a while loop like the following. While loops are preferred over cursors for being much faster. Assuming that table name is MYTABLE:

CREATE TABLE #temp
(                               
aa            numeric(5,0)  identity,                            
id            int           not null,
id_type       int           not null,
id_ref        int           not null
)

CREATE TABLE #results
(                                                        
id            int           not null,
concatenation varchar(1000) not null,
)

insert into #temp
select id, id_type, id_ref from MYTABLE order by id

declare @aa int, @maxaa int, @idOld int, @idNew int
declare @str1 varchar(1000), @str2 varchar(1000)

set @aa = 1
set @maxaa = (select max(aa) from #temp) 
set @idNew = (select id from #temp where aa = 1) 
, @idOld = @idNew

while @aa <= @maxaa 
    begin
        set @idNew = (select id from #temp where aa = @aa) 
        IF @idNew = @idOld
          BEGIN
             set @str1 = @str1 + convert(varchar,(select id_type from #temp where aa = @aa)) + ','  
             , @str2 = @str2 + convert(varchar,(select id_ref from #temp where aa = @aa)) + ','

             IF @aa = @maxaa  
             insert into #results (id, concatenation) 
             VALUES (@idOld, left(@str1,len(@str1) - 1) + ':' + left(@str2,len(@str2) - 1) )

          END
        ELSE
          BEGIN
             insert into #results (id, concatenation) 
             VALUES (@idOld, left(@str1,len(@str1) - 1) + ':' + left(@str2,len(@str2) - 1) )
             set @str1 = NULL, @str2 = NULL
             set @str1 = @str1 + convert(varchar,(select id_type from #temp where aa = @aa)) + ','  
             , @str2 = @str2 + convert(varchar,(select id_ref from #temp where aa = @aa)) + ',' 

             IF @aa = @maxaa  
             insert into #results (id, concatenation) 
             VALUES (@idNew, left(@str1,len(@str1) - 1) + ':' + left(@str2,len(@str2) - 1) )
          END

        set @idOld = @idNew 
        set @aa = @aa+1
    end

select * from #results

EDIT The following version is about 45% faster

CREATE TABLE #temp
(                               
aa            numeric(5,0)  identity,                            
id            int           not null,
id_type       int           not null,
id_ref        int           not null
)

CREATE TABLE #results
(                                                        
id            int           not null,
concatenation varchar(1000) not null,
)

insert into #temp
select id, id_type, id_ref from MYTABLE order by id
declare @aa int, @maxaa int, @idOld int, @idNew int
declare @str1 varchar(1000), @str2 varchar(1000), @j int

set @aa = 1
set @maxaa = (select max(aa) from #temp) 
set @idNew = (select id from #temp where aa = 1) 
, @idOld = @idNew
set @str1 = ':'

while @aa <= @maxaa 
    begin
        set @idNew = (select id from #temp where aa = @aa) 
        IF @idNew = @idOld
          BEGIN
             set @str2 = (select convert(varchar,id_type) + ':' + convert(varchar,id_ref) from #temp where aa = @aa)
             set @j = (select charindex(':',@str2))
             set @str1 = str_replace(@str1, ':', substring(@str2,1,@j - 1) + ',:') + right(@str2,len(@str2) - @j) + ',' 

             IF @aa = @maxaa  
             insert into #results (id, concatenation) 
             VALUES (@idOld, left(str_replace(@str1, ',:', ':'),len(@str1) - 2) )

          END
        ELSE
          BEGIN
             insert into #results (id, concatenation) 
             VALUES (@idOld, left(str_replace(@str1, ',:', ':'),len(@str1) - 2) )
             set @str1 = ':'
             set @str2 = (select convert(varchar,id_type) + ':' + convert(varchar,id_ref) from #temp where aa = @aa)
             set @j = (select charindex(':',@str2))
             set @str1 = str_replace(@str1, ':', substring(@str2,1,@j - 1) + ',:') + right(@str2,len(@str2) - @j) + ','

             IF @aa = @maxaa  
             insert into #results (id, concatenation) 
             VALUES (@idNew, left(str_replace(@str1, ',:', ':'),len(@str1) - 2) )
          END

        set @idOld = @idNew 
        set @aa = @aa+1
    end

select * from #results

Answer 2

Ok, forgive me if I'm missing something crucial here because I don't know the first thing about Sybase. But in mysql, this is absurdly simple so I figured it couldn't be as bad as the answers so far. So pulling from documentation that may or may not be relevant:

SELECT id, LIST(id_type) + ":" + LIST(id_ref) AS concatentation

Please inform me if I've misread something and I'll delete this.

Answer 3

Use the row level function.

your query:

select distinct id ,fn(id) from table1

function:

fn(@id int)
(
declare @res varchar
select @res = @res+id_ref+"," from table1 where id=@id
return @res
)