c:\@Work\Perl>perl -wMstrict -le
"my $y = '2017-01-29 11:30:07.370';
 my $x;
 ;;
 ($x) = $y =~ m{ (\d{4}) - (\d{2} - \d{2}) \s+ (\d{2} : \d{2}) .* }xms;
 print qq{A: x '$x'  y '$y'};
 ;;
 ($x = $y) =~ s{ (\d{4}) - (\d{2} - \d{2}) \s+ (\d{2} : \d{2}) .* }
               {$2-$1 $3}xms;
 print qq{B: x '$x'  y '$y'};
 ;;
 $x = $y =~ s{ (\d{4}) - (\d{2} - \d{2}) \s+ (\d{2} : \d{2}) .* }
             {$2-$1 $3}xms;
 print qq{C: x '$x'  y '$y'};
"
A: x '2017'  y '2017-01-29 11:30:07.370'
B: x '01-29-2017 11:30'  y '2017-01-29 11:30:07.370'
C: x '1'  y '01-29-2017 11:30'