Hardly the shortest, but below is a one line version obtained using very basic simplifications of your code ($_ =~ eliminated. while (<STDIN>) replaced with the n command line option. $ and \n replaced with the l command line .) 
perl -nle "/TABLE;(.*)/?($t=$1):/COLUMN;([^;]*)/&&print qq{$t.$1}"

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In reply to Re: regular expression to get the tablename.column_name by ikegami
in thread regular expression to get the tablename.column_name by greatshots

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