Listing 1: Measurements for Instruments

SELECT f.InstrId
     , (SELECT TOP 1 m.Msr1 FROM dbo.InstrStats AS m
         WHERE m.InstrId = f.InstrId AND m.Msr1 IS NOT NULL
         ORDER BY m.CreateTime DESC) AS l_msr1
     , (SELECT TOP 1 m.Msr2 FROM dbo.InstrStats AS m
         WHERE m.InstrId = f.InstrId AND m.Msr2 IS NOT NULL
         ORDER BY m.CreateTime DESC) AS l_msr2
     , (SELECT TOP 1 m.Msr3 FROM dbo.InstrStats AS m
         WHERE m.InstrId = f.InstrId AND m.Msr3 IS NOT NULL
         ORDER BY m.CreateTime DESC) as l_msr3
     , (SELECT TOP 1 m.Msr4 from dbo.InstrStats AS m
         WHERE m.InstrId = f.InstrId AND m.Msr4 IS NOT NULL
         ORDER BY m.CreateTime DESC) AS l_msr4
     , (SELECT TOP 1 m.Msr5 FROM dbo.InstrStats AS m
         WHERE m.InstrId = f.InstrId AND m.Msr5 IS NOT NULL
         ORDER BY m.CreateTime DESC) AS l_msr5
     , (SELECT TOP 1 m.Msr6 FROM dbo.InstrStats AS m
         WHERE m.InstrId = f.InstrId AND m.Msr6 IS NOT NULL
         ORDER BY m.CreateTime DESC) AS l_msr6
FROM dbo.InstrStats AS f
GROUP BY f.InstrId