in reply to Re^2: regular expression to get the tablename.column_name
in thread regular expression to get the tablename.column_name

Unlike the OP's version, your version won't handle blank lines or lines other than TABLE and COLUMN properly. If that's acceptable, then the following is even shorter: 
perl -nle "/TABLE;(.*)/?($t=$1):/;(.*);/&&print qq($t.$1)" o33.txt

[download]

In Section Seekers of Perl Wisdom