Select and merge rows in a table in SQL Stored procedure - sql

Question

Have a temp table with schema: ID | SeqNo | Name
ID - Not unique
SeqNo - Int (can be 1,2 or 3). Sort of ID+SeqNo as Primary key
Name - Any text
And sample data in the table like this
1 | 1 | RecordA
2 | 1 | RecordB
3 | 1 | RecordC
1 | 2 | RecordD
4 | 1 | RecordE
5 | 1 | RecordF
3 | 1 | RecordG
Need to select from this table and output like
1 | RecordA/RecordD
2 | RecordB
3 | RecordC/RecordG
4 | RecordE
5 | RecordF
Need to do this without cursor.

Answer 1

If SeqNo is limited to 1,2,3:
select id, a.name + coalesce('/'+b.name, '') + coalesce('/'+c.name, '')
from myTable a
left outer join myTable b on a.id=b.id and b.seqno = 2
left outer join myTable c on a.id=c.id and c.seqno = 3
where a.seqno = 1;
If SeqNo is open ended you can deploy a recursive cte:
;with anchor as (
select id, name, seqno
from myTable
where seqno=1)
, recursive as (
select id, name, seqno
from anchor
union all
select t.id, r.name + '/' + t.name, t.seqno
from myTable t
join recursive r on t.id = r.id and r.seqno+1 = t.seqno)
select id, name from recursive;

Answer 2

If you know SeqNo will never be more than 3:
select Id, Names = stuff(
max(case when SeqNo = 1 then '/'+Name else '' end)
+ max(case when SeqNo = 2 then '/'+Name else '' end)
+ max(case when SeqNo = 3 then '/'+Name else '' end)
, 1, 1, '')
from table1
group by Id
Otherwise, something like this is the generic solution to an arbitrary number of items:
select Id, Names = stuff((
select '/'+Name from table1 b
where a.Id = b.Id order by SeqNo
for xml path (''))
, 1, 1, '')
from table1 a
group by Id
Or write a CLR UDA.
Edit: had the wrong alias on the correlated table!
Edit2: another version, based on Remus's recursion example. I couldn't think of any way to select only the last recursion per Id, without aggregation or sorting. Anybody know?
;with
myTable as (
select * from (
values
(1, 1, 'RecordA')
, (2, 1, 'RecordB')
, (3, 1, 'RecordC')
, (1, 2, 'RecordD')
, (4, 1, 'RecordE')
, (5, 1, 'RecordF')
, (3, 2, 'RecordG')
) a (Id, SeqNo, Name)
)
, anchor as (
select id, name = convert(varchar(max),name), seqno
from myTable where seqno=1
)
, recursive as (
select id, name, seqno
from anchor
union all
select t.id, r.name + '/' + t.name, t.seqno
from myTable t
join recursive r on t.id = r.id and r.seqno+1 = t.seqno
)
select id, name = max(name)
from recursive
group by id;
---- without aggregation, we get 7 rows:
--select id, name
--from recursive;

Answer 3

The solution is good. I have a similar issue, but here I am using 2 different tables. ex:
table1
1 | 1 |
2 | 3 |
3 | 1 |
4 | 2 |
5 | 1 |
1 | 2 |
1 | 3 |
4 | 1 |
5 | 2 |
2 | 2 |
4 | 3 |
table2
1 | RecordA
2 | RecordB
3 | RecordC
I want to get the data from two tables and display in the below format.
1 | RecordA,RecordB,RecordC|
2 | RecordB,RecordC|
3 | RecordA |
4 | RecordA,RecordB,RecordC|
5 | RecordA,RecordB |