Query return result in SSMS but not in C#

Question

My database developer gave me a SQL query and it runs successfully in SSMS.

USE testdb 

DECLARE @Pipeline TABLE 
  ( 
     pipeline         VARCHAR(4000), 
     unitcode         VARCHAR(4000), 
     designareanumber VARCHAR(4000), 
     nameofnote       VARCHAR(4000) 
  ) 

INSERT INTO @Pipeline 
SELECT pipeline, 
       unitcode, 
       designareanumber, 
       nameofnote 
FROM   (SELECT pp.oid               AS OID, 
               nmpp.itemname        AS ItemName, 
               nmpl.itemname        AS Pipeline, 
               tn.trainnumber       AS TrainNumber, 
               uc.unitcode          AS UnitCode,                  

        FROM   jrtepipepart pp 
               JOIN jnameditem nmpp 
                 ON pp.oid = nmpp.oid 
               JOIN xcontainsnote xcn 
                 ON pp.oid = xcn.oidorigin 

        WHERE  gn.text <> '' 
               AND ( nmpps.itemname = 'Piping_New' 
                      OR nmpps.itemname = 'Piping_Modified/Tie_In' ) 
        --where gn.Text like '%000002A_TP08' AND (nmpps.ItemName = 'Piping_New' OR nmpps.ItemName = 'Piping_Modified/Tie_In')
        UNION ALL 
        SELECT hs.oid               AS OID, 
               nmhs.itemname        AS ItemName, 
               nmpl.itemname        AS Pipeline, 
               tn.trainnumber       AS TrainNumber, 
               uc.unitcode          AS UnitCode,                    
        FROM   jhgrsupport hs 
               JOIN jnameditem nmhs 
                 ON hs.oid = nmhs.oid                                       
        WHERE  gn.text <> '' 
               AND ( nmpps.itemname = 'Piping_New' 
                      OR nmpps.itemname = 'Piping_Modified/Tie_In' ))A     
SELECT pipeline, 
       unitcode, 
       designareanumber, 
       ( Stuff((SELECT Cast('; ' + nameofnote AS VARCHAR(max)) 
                FROM   @Pipeline p2 
                WHERE  ( p2.pipeline = p1.pipeline 
                         AND p2.unitcode = p1.unitcode 
                         AND p2.designareanumber = p1.designareanumber 
                         AND nameofnote NOT IN ( 'Note 1', '' ) ) 
                FOR xml path ('')), 1, 2, '') ) AS NameOfNote 
FROM   @Pipeline p1 
WHERE  nameofnote NOT IN ( 'Note 1', '' ) 
GROUP  BY pipeline, 
          unitcode, 
          designareanumber 

When I run above query in OleDbDataAdapter it return 0 rows. I have tried adding SET NOCOUNT ON at start of the query but not working. I have increased set-timeout property.

Answer 1

Removed USE testdb , added SET NOCOUNT ON and added database name before table names resolved this issue.