仅在SQL Server中某个相应的列条件='y'之后才查询列条件='x'的行

Question

apologies in advance if I'm missing critical information, I'm very new to this.

I have a massive database of devices, receivers, and corresponding value that counts up one as messages are received.

For example, here is my original table of data :

+-----------------------+--------+-------+------------+-------+
|received_time          |receiver|device |message_type| value | 
+-----------------------+--------+-------+------------+-------+                                          
|2019-07-17 7:50:14.850 | R1     |     D1|      2     |   1   |
|2019-07-17 7:50:14.853 | R1     |     D1|      1     |  NULL | 
|2019-07-17 7:50:14.947 | R1     |     D1|      2     |   1   |
|2019-07-17 7:50:14.957 | R1     |     D1|      1     |  NULL |
|2019-07-17 7:50:15.060 | R2     |     D1|      2     |   1   | 
|2019-07-17 7:50:15.067 | R3     |     D1|      2     |   1   |
|2019-07-17 7:50:15.073 | R3     |     D1|      1     |  NULL |
|2019-07-17 7:50:15.170 | R4     |     D2|      1     |  NULL |
|2019-07-17 7:50:15.283 | R5     |     D2|      2     |   0   |
|2019-07-17 7:50:15.287 | R5     |     D2|      1     |  NULL |
|2019-07-17 7:55:00.000 | R1     |     D2|      5     |  NULL |  
|2019-07-17 7:55:01.400 | R1     |     D2|      2     |   A   |
+-----------------------+--------+-------+------------+-------+

and so on...

OBJECTIVE

My objective is to query for the corresponding value only where a specific message_type is listed. The problem is, this value is on a different row. This could be message_type = '5' , or message_type = '1' (whatever I'm currently looking for). The problem is, the only way I can think of to do this is by ordering by received_time but within a period of x seconds after the initial message_type condition has been met, however in some cases the '2' comes before the corresponding '1' message_type .

I have already tried different variations of the GROUP BY function, but this has been very confusing and I'm not sure where to go from here.

Attempt #1 - Not good

SELECT received_time, receiver, device, message_type, value,
    CASE
        WHEN message_type = '5' THEN --Select corresponding value 
                                     --where message_type = '2'
    END 
FROM table;

Attempt #2 - closer to what I'm trying to do

SELECT * FROM my_table
    WHERE message_type = '5' 
        SELECT * FROM my_table
            WHERE
                received_time BETWEEN (received_time - 3 seconds) 
                and (received_time + 3 seconds)
                and (device = device) --order by for each device?
                and (message_type = '5' or message_type = '2')

My expected table should look this if I want to search for message_type = 5:

+-----------------------+--------+-------+------------+-------+
|received_time          |receiver|device |message_type| value | 
+-----------------------+--------+-------+------------+-------+                                          
|2019-07-17 7:55:00.000 | R1     |     D2|      5     |  NULL |
|2019-07-17 7:55:01.400 | R1     |     D2|      2     |   A   | 
+-----------------------+--------+-------+------------+-------+

But expected table should look this if I want to search for message_type = 1:

+-----------------------+--------+-------+------------+-------+
|received_time          |receiver|device |message_type| value | 
+-----------------------+--------+-------+------------+-------+                                          
|2019-07-17 7:50:14.850 | R1     |     D1|      2     |   1   |
|2019-07-17 7:50:14.853 | R1     |     D1|      1     |  NULL | 
|2019-07-17 7:50:15.170 | R4     |     D2|      1     |  NULL |
|2019-07-17 7:50:15.283 | R5     |     D2|      2     |   0   |
+-----------------------+--------+-------+------------+-------+

This is a very tricky question to ask, and hard to explain. Any help is much appreciated, thank you!

Answer 1

As I understand your problem is that you need that for each message_type 1 or 5 find the corresponding message_type 2 and get the value, with the consideration that the type 2 could be before and after the type 1 or 5. The solution I am proposing here considers that the corresponding type 2 is the one closest to the original message (type 1 or 5).

I do this in 2 steps:

1. Calculate which type 2 is closest to the one I want to find:

   select t2.receiver, t2.device, t2.received_time, MIN(ABS(DATEDIFF(MILLISECOND, t.received_time, t2.received_time))) AS closest_received_time INTO #tmpClosest from my_table as t inner join my_table as t2 ON t.receiver = t2.receiver and t.device = t2.device where t.message_type = 2 AND t2.message_type = 1 --define here the type for the main message (1 or 5) GROUP BY t2.receiver, t2.device, t2.received_time

2. With this temp table then you can retrieve the value for the corresponding one

   SELECT tc.receiver, tc.device, tc.received_time, t.value FROM #tmpClosest AS tc INNER JOIN my_table AS t ON t.receiver = tc.receiver AND t.device = tc.device WHERE tc.closest_received_time = ABS(DATEDIFF(MILLISECOND, t.received_time, tc.received_time))