SELECT col_number,rate,get_equal_numbers(col_number,my_number) AS equals 
FROM destinations
WHERE equals >= 1 
ORDER BY equals DESC

#!/usr/bin/ruby

def get_routing_target(number)
   # number is a string
   routing_table = [
     "001" => "data1",
     "0012 => "data2",
     "00129" => "data3" ]
   for current_length in number.length .. 1
        if routing_table[number[0,current_length]] then
            return routing_table[number[0,current_length]
        end
   end
end

DROP FUNCTION IF EXISTS equal_chars_from_left;
DELIMITER $$
CREATE FUNCTION equal_chars_from_left(wanted TEXT, current_field TEXT)
  RETURNS INT
BEGIN
  DECLARE current_length INT;
  SET current_length = LENGTH(wanted);

  count_loop: LOOP
    IF SUBSTRING(current_field,1,current_length) = SUBSTRING(wanted,1,current_length) THEN
        LEAVE count_loop;
    END IF;
    SET current_length = current_length - 1;

    IF current_length = 0 THEN
      LEAVE count_loop;
    END IF;
    
  END LOOP;
  RETURN current_length;
END;
$$
DELIMITER ;

mysql> select destination,rate,equal_chars_from_left("1212313",destination) as equals from test order by equals desc limit 10;
+----------------+------+--------+
| destination    | rate | equals |
+----------------+------+--------+
| 1212313893101  | 0.97 |      7 |
| 12123105591    | 0.09 |      6 |
| 12123          | 0.98 |      5 |
| 12123235501917 | 0.07 |      5 |
| 121283339945   | 0.19 |      4 |
| 121243075      | 0.53 |      4 |
| 121251         | 0.69 |      4 |
| 1212626040     | 0.23 |      4 |
| 1212914454156  | 0.72 |      4 |
| 121251042914   | 0.46 |      4 |
+----------------+------+--------+
10 rows in set (6,35 sec)

SELECT destination,equal_chars_from_left('1212313',destination) as equals from test where destination like '1212313%'  UNION
SELECT destination,equal_chars_from_left('1212313',destination) as equals from test where destination like '121231%'  UNION
SELECT destination,equal_chars_from_left('1212313',destination) as equals from test where destination like '12123%'  UNION
SELECT destination,equal_chars_from_left('1212313',destination) as equals from test where destination like '1212%'  UNION
SELECT destination,equal_chars_from_left('1212313',destination) as equals from test where destination like '121%'  UNION
SELECT destination,equal_chars_from_left('1212313',destination) as equals from test where destination like '12%'  UNION
SELECT destination,equal_chars_from_left('1212313',destination) as equals from test where destination like '1%' 
ORDER BY equals DESC LIMIT 10;

+----------------+--------+
| destination    | equals |
+----------------+--------+
| 1212313893101  |      7 |
| 12123105591    |      6 |
| 12123          |      5 |
| 12123235501917 |      5 |
| 12120247005    |      4 |
| 121283339945   |      4 |
| 12125241424986 |      4 |
| 1212426494209  |      4 |
| 1212116831     |      4 |
| 121284268      |      4 |
+----------------+--------+
10 rows in set (2,10 sec)