Combine multiple results in a subquery into a single comma-separated value - sql-server

Question

I've got two tables:
TableA
------
ID,
Name
TableB
------
ID,
SomeColumn,
TableA_ID (FK for TableA)
The relationship is one row of TableA - many of TableB.
Now, I want to see a result like this:
ID Name SomeColumn
1. ABC X, Y, Z (these are three different rows)
2. MNO R, S
This won't work (multiple results in a subquery):
SELECT ID,
Name,
(SELECT SomeColumn FROM TableB WHERE F_ID=TableA.ID)
FROM TableA
This is a trivial problem if I do the processing on the client side. But this will mean I will have to run X queries on every page, where X is the number of results of TableA.
Note that I can't simply do a GROUP BY or something similar, as it will return multiple results for rows of TableA.
I'm not sure if a UDF, utilizing COALESCE or something similar might work?

Answer 1

Even this will serve the purpose
Sample data
declare #t table(id int, name varchar(20),somecolumn varchar(MAX))
insert into #t
select 1,'ABC','X' union all
select 1,'ABC','Y' union all
select 1,'ABC','Z' union all
select 2,'MNO','R' union all
select 2,'MNO','S'
Query:
SELECT ID,Name,
STUFF((SELECT ',' + CAST(T2.SomeColumn AS VARCHAR(MAX))
FROM #T T2 WHERE T1.id = T2.id AND T1.name = T2.name
FOR XML PATH('')),1,1,'') SOMECOLUMN
FROM #T T1
GROUP BY id,Name
Output:
ID Name SomeColumn
1 ABC X,Y,Z
2 MNO R,S

Answer 2

1. Create the UDF:
CREATE FUNCTION CombineValues
(
#FK_ID INT -- The foreign key from TableA which is used
-- to fetch corresponding records
)
RETURNS VARCHAR(8000)
AS
BEGIN
DECLARE #SomeColumnList VARCHAR(8000);
SELECT #SomeColumnList =
COALESCE(#SomeColumnList + ', ', '') + CAST(SomeColumn AS varchar(20))
FROM TableB C
WHERE C.FK_ID = #FK_ID;
RETURN
(
SELECT #SomeColumnList
)
END
2. Use in subquery:
SELECT ID, Name, dbo.CombineValues(FK_ID) FROM TableA
3. If you are using stored procedure you can do like this:
CREATE PROCEDURE GetCombinedValues
#FK_ID int
As
BEGIN
DECLARE #SomeColumnList VARCHAR(800)
SELECT #SomeColumnList =
COALESCE(#SomeColumnList + ', ', '') + CAST(SomeColumn AS varchar(20))
FROM TableB
WHERE FK_ID = #FK_ID
Select *, #SomeColumnList as SelectedIds
FROM
TableA
WHERE
FK_ID = #FK_ID
END

Answer 3

In MySQL there is a group_concat function that will return what you're asking for.
SELECT TableA.ID, TableA.Name, group_concat(TableB.SomeColumn)
as SomColumnGroup FROM TableA LEFT JOIN TableB ON
TableB.TableA_ID = TableA.ID

Answer 4

I think you are on the right track with COALESCE. See here for an example of building a comma-delimited string:
http://www.sqlteam.com/article/using-coalesce-to-build-comma-delimited-string

Answer 5

You may need to provide some more details for a more precise response.
Since your dataset seems kind of narrow, you might consider just using a row per result and performing the post-processing at the client.
So if you are really looking to make the server do the work return a result set like
ID Name SomeColumn
1 ABC X
1 ABC Y
1 ABC Z
2 MNO R
2 MNO S
which of course is a simple INNER JOIN on ID
Once you have the resultset back at the client, maintain a variable called CurrentName and use that as a trigger when to stop collecting SomeColumn into the useful thing you want it to do.

Answer 6

Assuming you only have WHERE clauses on table A create a stored procedure thus:
SELECT Id, Name From tableA WHERE ...
SELECT tableA.Id AS ParentId, Somecolumn
FROM tableA INNER JOIN tableB on TableA.Id = TableB.F_Id
WHERE ...
Then fill a DataSet ds with it. Then
ds.Relations.Add("foo", ds.Tables[0].Columns("Id"), ds.Tables[1].Columns("ParentId"));
Finally you can add a repeater in the page that puts the commas for every line
<asp:DataList ID="Subcategories" DataKeyField="ParentCatId"
DataSource='<%# Container.DataItem.CreateChildView("foo") %>' RepeatColumns="1"
RepeatDirection="Horizontal" ItemStyle-HorizontalAlign="left" ItemStyle-VerticalAlign="top"
runat="server" >
In this way you will do it client side but with only one query, passing minimal data between database and frontend

Answer 7

I tried the solution priyanka.sarkar mentioned and the didn't quite get it working as the OP asked. Here's the solution I ended up with:
SELECT ID,
SUBSTRING((
SELECT ',' + T2.SomeColumn
FROM #T T2
WHERE WHERE T1.id = T2.id
FOR XML PATH('')), 2, 1000000)
FROM #T T1
GROUP BY ID

Answer 8

Solution below:
SELECT GROUP_CONCAT(field_attr_best_weekday_value)as RAVI
FROM content_field_attr_best_weekday LEFT JOIN content_type_attraction
on content_field_attr_best_weekday.nid = content_type_attraction.nid
GROUP BY content_field_attr_best_weekday.nid
Use this, you also can change the Joins

Answer 9

SELECT t.ID,
t.NAME,
(SELECT t1.SOMECOLUMN
FROM TABLEB t1
WHERE t1.F_ID = T.TABLEA.ID)
FROM TABLEA t;
This will work for selecting from different table using sub query.

Answer 10

I have reviewed all the answers. I think in database insertion should be like:
ID Name SomeColumn
1. ABC ,X,Y Z (these are three different rows)
2. MNO ,R,S
The comma should be at previous end and do searching by like %,X,%