How to concat one column of multiple rows (group by clause used in query) I had some issue while populating some data as per my requirements and that is as follows..

Table data: 

---------------------------------------------
EMPID  PROJ_TYPE  HOURS  ST_DATE    ED_DATE
---------------------------------------------
1      DEV        10     2013-1-1   2013-5-1
1      DEV        34     2013-5-2   2013-8-1
1      DEV        23     2013-8-2   2013-10-1
1      TEST       12     2014-1-1   2014-3-1
1      TEST       25     2014-3-2   2014-6-1


Here I want to fetch the employee data with hours, So as simple I wrote 

SELECT EMPID,
       PROJ_TYPE, 
       SUM(CASE WHEN PROJ_TYPE='DEV' THEN HOURS ELSE 0 END) DEV, 
       SUM(CASE WHEN PROJ_TYPE='TEST' THEN HOURS ELSE 0 END) TEST
FROM TABLE1
GROUP BY EMPID, PROJ_TYPE


Hence it is returning two rows as expected but here the twist I want only one row per employee. If employee have multiple PROJ_TYPE then it should combine both project values and return only one row.

Finally my result set should look like:

----------------------------
EMPID  PROJ     DEV  TEST
----------------------------
1     DEV/TEST  67   37


Hope I am clear please comment if any doubt on my question.
A pivot will work for this

Test Data:

Declare @Test Table
(
 EMPID          Int
,PROJ_TYPE      NVarchar(4)
,HOURS          Int
,ST_DATE        Date
,ED_DATE        Date
);
Insert Into @Test
(EMPID, PROJ_TYPE, HOURS, ST_DATE, ED_DATE)
Values ('1', 'DEV','10','2013-1-1','2013-5-1')
        ,('1', 'DEV','34','2013-5-2','2013-8-1')
        ,('1', 'DEV','23','2013-8-2','2013-10-1')
        ,('1', 'TEST','12','2014-1-1','2014-3-1')
        ,('1', 'TEST','25','2014-3-2','2014-6-1')
        ,('2', 'DEV','7','2013-5-2','2013-8-1')
        ,('2', 'DEV','14','2013-8-2','2013-10-1')
        ,('2', 'TEST','12','2014-1-1','2014-3-1')
        ,('2', 'TEST','19','2014-3-2','2014-6-1')
        ,('3', 'DEV','34','2013-5-2','2013-8-1')
        ,('3', 'DEV','8','2013-8-2','2013-10-1')
        ,('3', 'TEST','12','2014-1-1','2014-3-1')
        ,('3', 'TEST','7','2014-3-2','2014-6-1')
        ,('3', 'DEV','23','2013-8-2','2013-10-1')
        ,('3', 'TEST','18','2014-1-1','2014-3-1')
        ,('4', 'TEST','25','2014-3-2','2014-6-1');


Query:

Select      EMPID
            ,IsNull(DEV,0) As DEV
            ,IsNull(TEST,0) As TEST
From        (
            Select      EMPID
                        ,PROJ_TYPE
                        ,HOURS
            From        @Test
            ) sq
    Pivot   (
            Sum(HOURS)
            For PROJ_TYPE In ([DEV],[TEST])
            ) piv;


SQL Fiddle: 
https://dbfiddle.uk/?rdbms=sqlserver_2017&amp;fiddle=6d9a0ceb9dbf13e8af351822733c4607