mysql - How to select all items in column by column name getJSON and php -

i have getjson call php function returns items in column column name. php function.

public function getcertsbycategory($certcategory) {        $connection = $this -> connect();        return $this -> select("select '.$certcatogory.' cert_catalog");     } 

this function data:

function certname(certcategory) {        $('#certificationname').empty();        console.log(certcategory);        $.getjson('json_data.php', { method: 'getcertsbycategory', certcategory: certcategory }, function(data) {           console.log(data);           $.each(data, function(key, value) {              console.log(value);              $('#certificationname').append('<option value="' + value + '">' + value + '</option>');           });        });      } 

why getting 2 dots values? looks in chrome developer tools.

10: object ..: ".." __proto__: object 11: object ..: ".." __proto__: object