Select record between two IP ranges

Question

I have a table which stores a ID, Name, Code, IPLow, IPHigh such as:

1, Lucas, 804645, 192.130.1         


        

Answer 1

Consider something like this example to convert the address into a number.

CREATE FUNCTION dbo.IPAddressAsNumber (@IPAddress AS varchar(15))
RETURNS bigint
BEGIN
RETURN
 CONVERT (bigint,
  CONVERT(varbinary(1), CONVERT(int, PARSENAME(@IPAddress, 4))) +
  CONVERT(varbinary(1), CONVERT(int, PARSENAME(@IPAddress, 3))) +
  CONVERT(varbinary(1), CONVERT(int, PARSENAME(@IPAddress, 2))) +
  CONVERT(varbinary(1), CONVERT(int, PARSENAME(@IPAddress, 1))) )
END

and with that you could use standard operators like BETWEEN to find rows within the range you have in the table

DECLARE @t table (ID int, Name varchar(50), Code int, IPLow varchar(15), IPHigh varchar(15))
INSERT INTO @t VALUES 
 (1, 'Lucas', 804645, '192.130.1.1', '192.130.1.254'),
 (2, 'Maria', 222255, '192.168.2.1', '192.168.2.254'),
 (3, 'Julia', 123456, '192.150.3.1', '192.150.3.254')

SELECT * FROM @t
WHERE dbo.IPAddressAsNumber('192.168.2.50')
 BETWEEN dbo.IPAddressAsNumber(IPLow) AND dbo.IPAddressAsNumber(IPHigh)

The scheme essentially uses PARSENAME to isolate each part of the address, converts each part into a SQL binary string, concatenating the strings together to get a single SQL binary string representing the address, and shows the result as a bigint.

In a textual representation of hexadecimal values think of this as smashing the 4 parts together 192(0xC0) + 168(0xA8) + 2(0x02) + 50(0x32) into 0xC0A80232. When you turn that combined string into its binary digits (0s and 1s) you would end up with something that could be thought of as the address in a binary form used by the network stack in address routing and subnet masking tables. When you turn that into a number in the form of an unsigned integer (or in this case a bigint) you get 3232236082.

Interestingly this scheme gives you a "number" that can be used in place of the original address in lots of ways. You can for example ping the number 2130706433 instead of the address 127.0.0.1 -- the name resolver in Windows will convert it similarly to how DNS is used to find the address of a hostname.

For the sake of completeness, here is another function that can be used to convert the number form back into the standard string form

CREATE FUNCTION dbo.IPAddressFromNumber (@IPNumber AS bigint)
RETURNS varchar(15)
BEGIN
RETURN
 CONVERT (varchar(15),
  CONVERT(varchar(3), CONVERT(int, SUBSTRING(CONVERT(varbinary(4), @IPNumber), 1,1))) + '.' +
  CONVERT(varchar(3), CONVERT(int, SUBSTRING(CONVERT(varbinary(4), @IPNumber), 2,1))) + '.' +
  CONVERT(varchar(3), CONVERT(int, SUBSTRING(CONVERT(varbinary(4), @IPNumber), 3,1))) + '.' +
  CONVERT(varchar(3), CONVERT(int, SUBSTRING(CONVERT(varbinary(4), @IPNumber), 4,1))) )
END