01.
SELECT
02.
[s2].[id],
03.
[sn].[serial_num],
04.
[sn].[maxDate] ,
05.
[a].[measured_left]
06.
FROM
07.
(SELECT
08.
[s].[serial_num],
09.
( SELECT MAX([date_time])
10.
FROM [serial_numbers]
11.
WHERE [s].[serial_num] = [serial_num] ) AS [maxDate]
12.
FROM
13.
[serial_numbers] AS [s]
14.
GROUP BY [s].[serial_num]) AS [sn]
15.
JOIN [serial_numbers] AS [s2]
16.
ON [sn].[serial_num] = [s2].[serial_num]
17.
AND [sn].[maxDate] = [s2].[date_time]
18.
JOIN [audio_tester] AS [a]
19.
ON [a].[serial_num] = [s2].[id]