Something like this may be - 

source:
Load * inline [
Datetime
2020-11-05 08:37:50
2020-11-05 08:37:51
2020-11-05 08:37:52
2020-11-05 08:37:53
2020-11-05 08:37:54
2020-11-05 08:37:55
2020-11-05 08:37:56
2020-11-05 08:37:57
2020-11-05 08:37:58
2020-11-05 08:37:59
2020-11-05 08:38:00
2020-11-05 08:38:01
2020-11-05 08:38:02
2020-11-05 08:38:03
2020-11-05 08:38:04
2020-11-05 08:38:05
2020-11-05 08:38:06
2020-11-05 08:38:07
2020-11-05 08:38:08
2020-11-05 08:38:09
2020-11-05 08:38:10
];

NoConcatenate
Final:
Load Datetime
resident source
Where Mod(Second(Datetime),10)=0
;

Drop table source;