Stored procedure with inner join using coalesce - sql-server

Question

I have a simple table tblAllUsers which stores simple values like Name,Date Of Birth etc of a UserId.
Another table tblInterest stores the interest(s) of a UserId.Here a user may have any number of Interest and are stored seperately in separate rows :
Create table tblInterest
(
Id int primary key identity,
UserId varchar(10),
InterestId int,
Interest varchar(20)
)
So when i want to display the set of Interest together of a particular user, I use the below query :
DECLARE #listStr VARCHAR(MAX)
SELECT #listStr = COALESCE(#listStr + ', ' ,'') + Interest FROM tblInterest where UserId=#UserId
SELECT #listStr
Now, want to display a users info from both these tables wherein the Interest(S) are displayed in ONE string.
I have tried the below ;
Create proc spPlayersGridview
#listStr VARCHAR(MAX)
as
begin
Select tblAllUsers.Category, tblAllUsers.DOB, tblAllUsers.FirstName, tblAllUsers.LastName, tblAllUsers.City, tblAllUsers.State,
#listStr = COALESCE(#listStr + ', ' ,'') + tblInterest.Interest
from tblAllUsers
INNER JOIN tblInterest
ON tblAllUsers.UserId=tblInterest.UserId
where Category='Player'
end
throws an exception "A SELECT statement that assigns a value to a variable must not be combined with data-retrieval operations."

Answer 1

I had a similar problem a while back, and a bit of SQL STUFF magic helps - Maybe it will work for you as well.
CREATE PROC spPlayersGridview
AS
BEGIN
SELECT
tblAllUsers.Category
, tblAllUsers.DOB
, tblAllUsers.FirstName
, tblAllUsers.LastName
, tblAllUsers.City
, tblAllUsers.State
, listStr = STUFF((
SELECT ',' + tblInterest.Interest
FROM tblInterest
WHERE tblAllUsers.UserId=tblInterest.UserId
ORDER BY tblInterest.Interest
FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)'), 1, 1, '')
FROM tblAllUsers
WHERE Category='Player'
END
Hope it helps - For more reading look at: https://msdn.microsoft.com/en-us/library/ms188043.aspx