You need to indent your code. Not indenting correctly makes it hard to see what really happens. This is how it should look:

for my $data_pair (@data_list) {
    if($data_pair->{'key'} eq 'correct') {

        my $cor= $data_pair->{'value'};

        if($data_pair->{'key'} eq 'date') {
            my $date = $data_pair->{'value'};
            ...
        }
     }
}
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It is now clear that getting to the my $date = $data_pair ... is impossible.

Another issue is that you have a syntax error in your script. I can't see how you'd ever be able to run it:

         $sql_content .= "
INSERT IGNORE INTO correct SET
       text='".$cor."',
       date='".$date."';
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Again, formatting the code better and using DBI placeholders or just interpolation would help you see it (interpolation: you can write text='$cor' in stead of text='" . $cor . "'.

So my message is: keeping your code tidy is a great way of avoiding the kind of confusion that caused you to ask here in the first place.