You can't create a hash like

%fetch= (sse_date => 4934056723, bld_num => 7.3.998.0.0,
        sse_date => 4934099999, bld_num => 7.3.1003.0.0,
        sse_date => 4949999999, bld_num => 7.3.1089.0.0);
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because each key (such as "sse_date") can only appear once in a given hash. So that code will simply produce a hash with two keys and effectively one row of data. Rather I assume you mean that you want to have an array of hashes, something like

my @fetch = ({sse_date => 4934056723, bld_num => '7.3.998.0.0'},
             {sse_date => 4934099999, bld_num => '7.3.1003.0.0'},
             ...
            );
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In that case you would see something like

my @sorted = map { $_->{bld_num} } sort { $a->{sse_date} <=> $b->{sse_
+date} } @fetch;
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and go from there.