SELECT A.[DateTime]
 ,A.[TagName]
 ,A.[Value]
FROM [v_StringHistory] A
INNER JOIN
    (SELECT MAX(B.[DateTime]) [MaxDate]
         ,B.[TagName]
    FROM [v_StringHistory] B
    GROUP BY B.[TagName]) MD
      ON MD.[TagName] = A.[TagName]
           AND A.[DateTime] = MD.MaxDate
WHERE A.[TagName] = 'ERecipeRunning'
    OR A.[TagName] = 'PRecipeRunning'

SELECT  sh.[DateTime],
        sh.[TagName],
        sh.[Value]
  FROM  [v_StringHistory] sh
WHERE   sh.[TagName] in( 'ERecipeRunning', 'PRecipeRunning' )
  and   sh.[DateTime] =(
        select  Max( [DateTime] )
        from    [v_StringHistory]
        where   [TagName] = sh.[TagName] );