How to get first occurrence of flag 1 record and last occurrence flag 0 record based on time

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I have list of records as given below in ms sql table

time	                       flag
2018-04-18 16:24:08.0000000     0
2018-04-18 16:14:08.0000000	1
2018-04-18 16:04:08.0000000	0
2018-04-18 15:54:08.0000000	0
2018-04-18 15:44:08.0000000	1
2018-04-18 15:34:08.0000000	1
2018-04-18 15:24:08.0000000	0
2018-04-18 15:04:08.0000000	1
2018-04-18 14:54:08.0000000	1
2018-04-18 14:44:08.0000000	0

how to get first occurrence of  flag 1 record(only one record that has occurred 1 st time based on time) and the last occurrence of flag 0 record(only one record that has occurred last)
Result  should be :
2018-04-18 14:54:08.0000000	1
2018-04-18 16:24:08.0000000	0
(two records)

or else 
2018-04-18 14:54:08.0000000	1   2018-04-18 16:24:08.0000000	0(single record)

What I have tried:

I have tried using Rownumber() function but i havent get expected result

Posted 20-Apr-18 21:59pm

chandubbbb

Updated 21-Apr-18 0:02am

v3

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OriginalGriff · Answer 1 · 2018-04-20T23:07:00

Solution 1

Try:

SQL

SELECT CASE WHEN Flag = 1 THEN MAX([Time]) 
                          ELSE MIN([Time]) 
                          END AS [Time], 
       Flag
FROM MyTable 
GROUP BY Flag

Posted 20-Apr-18 23:07pm

OriginalGriff

Updated 20-Apr-18 23:08pm

v2

Wendelius · Answer 2 · 2018-04-21T00:03:00

Solution 2

One way is to use a correlated NOT EXISTS condition. Something like

SQL

SELECT * 
FROM TableNameGoesHere t1
WHERE t1.Flag = 1
AND   NOT EXISTS ( SELECT 1
                   FROM TableNameGoesHere t2
                   WHERE t2.Flag = 1
                   AND   t2.Time < t1.Time)

Posted 21-Apr-18 0:03am

Wendelius