Select Colmn, From Table, Where ....
Select Colmn, From Table2, Where ....
Select Colmn, From Table3,Table4 Where ....

Select Colmn, From Table3,Table4 Where ....

Select Colmn,
  From Table3 ,
  Table4
   Where ....

perl -ne '$ = $/; print for /sfroms+([w,]+)/ig' input.txt

$ cat input.txt
Select Colmn, From Table, Where ....
Select Colmn, From Table2, Where ....
Select Colmn, From Table3,Table4 Where ....

$ perl -ne '$ = $/; print for /sfroms+([w,]+)/ig' input.txt
Table,
Table2,
Table3,Table4

$ cat input.txt
Select Colmn, From Table, Where ....
Select Colmn, From Table2, Where ....
Select Colmn, From Table3,
Table4
Where ....
$
$ sed -e 's/.*From //' -e 's/Where.*$//' -e '/^$/d' input.txt
Table,
Table2,
Table3,
Table4

perl -ne '$/=undef; print $_ . "n" for /(?<=from)s*(S*s*S*)s*(?=where)/ig' file

$ cat file
Select Colmn, From Table, Where ....
Select Colmn, From Table2, Where ....
Select Colmn, From Table3,Table4 Where ....
Select Colmn,
  From Table5,
  Table6
   Where ....

$ perl -ne '$/=undef; print $_ . "n" for /(?<=from)s*(S*s*S*)s*(?=where)/ig' file
Table,
Table2,
Table3,Table4
Table5,
  Table6