Convert integer to hex and hex to integer

So I have this query working (where signal_data is a column) in Sybase but it doesn't work in Microsoft SQL Server:

HEXTOINT(SUBSTRING((INTTOHEX(signal_data)),5,2)) as Signal

I also have it in Excel (where A1 contains the value):

=HEX2DEC(LEFT(DEC2HEX(A1),LEN(DEC2HEX(A1))-2))

Does anyone know how I would do this in SQL Server?

Convert INT to hex:

SELECT CONVERT(VARBINARY(8), 16777215)

Convert hex to INT:

SELECT CONVERT(INT, 0xFFFFFF)

Update 2015-03-16

The above example has the limitation that it only works when the HEX value is given as an integer literal. For completeness, if the value to convert is a hexadecimal string (such as found in a varchar column) use:

-- If the '0x' marker is present:
SELECT CONVERT(INT, CONVERT(VARBINARY, '0x1FFFFF', 1))

-- If the '0x' marker is NOT present:
SELECT CONVERT(INT, CONVERT(VARBINARY, '1FFFFF', 2))

Note: The string must contain an even number of hex digits. An odd number of digits will yield an error.

More details can be found in the "Binary Styles" section of CAST and CONVERT (Transact-SQL). I believe SQL Server 2008 or later is required.

Actually, the built-in function is named master.dbo.fn_varbintohexstr.

So, for example:

SELECT 100, master.dbo.fn_varbintohexstr(100)

Gives you

100 0x00000064

SQL Server equivalents to Excel's string-based DEC2HEX, HEX2DEC functions:

--Convert INT to hex string:
PRINT CONVERT(VARCHAR(8),CONVERT(VARBINARY(4), 16777215),2) --DEC2HEX

--Convert hex string to INT:
PRINT CONVERT(INT,CONVERT(VARBINARY(4),'00FFFFFF',2)) --HEX2DEC

It is possible using the function FORMAT available on SQL Server 2012 and above

select FORMAT(10,'x2')

Results in:

0a

Convert int to hex:

SELECT FORMAT(512+255,'X')

Here is the function for SQL server which converts integer value into its hexadecimal representation as a varchar. It should be easy to adapt to other database types

For example:

SELECT dbo.ToHex(4095) --> FFF

SQL:

CREATE FUNCTION ToHex(@value int)
RETURNS varchar(50)
AS
BEGIN
	DECLARE @seq char(16)
	DECLARE @result varchar(50)
	DECLARE @digit char(1)
	SET @seq = '0123456789ABCDEF'

	SET @result = SUBSTRING(@seq, (@value%16)+1, 1)

	WHILE @value > 0
	BEGIN
		SET @digit = SUBSTRING(@seq, ((@value/16)%16)+1, 1)
		
		SET @value = @value/16
		IF @value <> 0 SET @result = @digit + @result
	END 

    RETURN @result
END
GO

The traditonal 4 bit hex is pretty direct. Hex String to Integer (Assuming value is stored in field called FHexString) :

CONVERT(BIGINT,CONVERT(varbinary(4),
				(SELECT master.dbo.fn_cdc_hexstrtobin(
					
					LEFT(FMEID_ESN,8)						
				))
				))

Integer to Hex String (Assuming value is stored in field called FInteger):

(SELECT master.dbo.fn_varbintohexstr(CONVERT(varbinary,CONVERT(int,
					FInteger
				))))

Important to note is that when you begin to use bit sizes that cause register sharing, especially on an intel machine, your High and Low and Left and Rights in the registers will be swapped due to the little endian nature of Intel. For example, when using a varbinary(3), we're talking about a 6 character Hex. In this case, your bits are paired as the following indexes from right to left "54,32,10". In an intel system, you would expect "76,54,32,10". Since you are only using 6 of the 8, you need to remember to do the swaps yourself. "76,54" will qualify as your left and "32,10" will qualify as your right. The comma separates your high and low. Intel swaps the high and lows, then the left and rights. So to do a conversion...sigh, you got to swap them yourselves for example, the following converts the first 6 of an 8 character hex:

(SELECT master.dbo.fn_replvarbintoint(
				CONVERT(varbinary(3),(SELECT master.dbo.fn_cdc_hexstrtobin(
					--intel processors, registers are switched, so reverse them 
					
					
					----second half
					RIGHT(FHex8,2)+ --0,1 (0 indexed)
					LEFT(RIGHT(FHex8,4),2)+ -- 2,3 (oindex)
					--first half
					LEFT(RIGHT(FHex8,6),2) --4,5
					
				)))
				))

It's a bit complicated, so I would try to keep my conversions to 8 character hex's (varbinary(4)).

In summary, this should answer your question. Comprehensively.

Use master.dbo.fnbintohexstr(16777215) to convert to a varchar representation.

Maksym Kozlenko has a nice solution, and others come close to unlocking it's full potential but then miss completely to realized that you can define any sequence of characters, and use it's length as the Base. Which is why I like this slightly modified version of his solution, because it can work for base 16, or base 17, and etc.

For example, what if you wanted letters and numbers, but don't like I's for looking like 1's and O's for looking like 0's. You can define any sequence this way. Below is a form of a "Base 36" that skips the I and O to create a "modified base 34". Un-comment the hex line instead to run as hex.

declare @value int = 1234567890

DECLARE @seq varchar(100) = '0123456789ABCDEFGHJKLMNPQRSTUVWXYZ' -- modified base 34
--DECLARE @seq varchar(100) = '0123456789ABCDEF' -- hex
DECLARE @result varchar(50)
DECLARE @digit char(1)
DECLARE @baseSize int = len(@seq)
DECLARE @workingValue int = @value

SET @result = SUBSTRING(@seq, (@workingValue%@baseSize)+1, 1)

WHILE @workingValue > 0
BEGIN
    SET @digit = SUBSTRING(@seq, ((@workingValue/@baseSize)%@baseSize)+1, 1)

    SET @workingValue = @workingValue/@baseSize
    IF @workingValue <> 0 SET @result = @digit + @result
END 

select @value as Value, @baseSize as BaseSize, @result as Result

> Value, BaseSize, Result > > 1234567890, 34, T5URAA

I also moved value over to a working value, and then work from the working value copy, as a personal preference.

Below is additional for reversing the transformation, for any sequence, with the base defined as the length of the sequence.

declare @value varchar(50) = 'T5URAA'

DECLARE @seq varchar(100) = '0123456789ABCDEFGHJKLMNPQRSTUVWXYZ' -- modified base 34
--DECLARE @seq varchar(100) = '0123456789ABCDEF' -- hex
DECLARE @result int = 0
DECLARE @digit char(1)
DECLARE @baseSize int = len(@seq)
DECLARE @workingValue varchar(50) = @value

DECLARE @PositionMultiplier int = 1
DECLARE @digitPositionInSequence int = 0

WHILE len(@workingValue) > 0
BEGIN
    SET @digit = right(@workingValue,1)
	SET @digitPositionInSequence = CHARINDEX(@digit,@seq)
	SET @result = @result + ( (@digitPositionInSequence -1) * @PositionMultiplier)

	--select @digit, @digitPositionInSequence, @PositionMultiplier, @result

	SET @workingValue = left(@workingValue,len(@workingValue)-1)
	SET @PositionMultiplier = @PositionMultiplier * @baseSize
END 

select @value as Value, @baseSize as BaseSize, @result as Result

Declare @Dato xml
Set @Dato = Convert(xml, '<dato>FF</dato>')
Select Cast( rw.value( 'xs:hexBinary( text()[1])' , 'varbinary(max)' ) as int ) From @Dato.nodes('dato') as T(rw)

The answer by Maksym Kozlenko is nice and can be slightly modified to handle encoding a numeric value to any code format. For example:

CREATE FUNCTION [dbo].[IntToAlpha](@Value int)
RETURNS varchar(30)
AS
BEGIN
    DECLARE @CodeChars varchar(100) 
    SET @CodeChars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
	DECLARE @CodeLength int = 26
    DECLARE @Result varchar(30) = ''
    DECLARE @Digit char(1)

    SET @Result = SUBSTRING(@CodeChars, (@Value % @CodeLength) + 1, 1)
	WHILE @Value > 0
    BEGIN
        SET @Digit = SUBSTRING(@CodeChars, ((@Value / @CodeLength) % @CodeLength) + 1, 1)
        SET @Value = @Value / @CodeLength
        IF @Value <> 0 SET @Result = @Digit + @Result
    END 

    RETURN @Result
END

So, a big number like 150 million, becomes only 6 characters (150,000,000 = "MQGJMU")

You could also use different characters in different sequences as an encrypting device. Or pass in the code characters and length of characters and use as a salting method for encrypting.

And the reverse:

CREATE FUNCTION [dbo].[AlphaToInt](@Value varchar(7))
RETURNS int
AS
BEGIN
    DECLARE @CodeChars varchar(100) 
    SET @CodeChars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
	DECLARE @CodeLength int = 26
    DECLARE @Digit char(1)
    DECLARE @Result int = 0
	DECLARE @DigitValue int
	DECLARE @Index int = 0
	DECLARE @Reverse varchar(7)
	SET @Reverse = REVERSE(@Value)

	WHILE @Index < LEN(@Value)
    BEGIN
        SET @Digit = SUBSTRING(@Reverse, @Index + 1, 1)
        SET @DigitValue = (CHARINDEX(@Digit, @CodeChars) - 1) * POWER(@CodeLength, @Index)
        SET @Result = @Result + @DigitValue
		SET @Index = @Index + 1
    END 
    RETURN @Result

Given:

declare @hexStr varchar(16), @intVal int

IntToHexStr:

select @hexStr = convert(varbinary, @intVal, 1)

HexStrToInt:

declare
	@query varchar(100),
	@parameters varchar(50)

select
	@query = 'select @result = convert(int,' + @hb + ')',
	@parameters = '@result int output'

exec master.dbo.Sp_executesql @query, @parameters, @intVal output

IIF(Fields!HIGHLIGHT_COLOUR.Value="","#FFFFFF","#" & hex(Fields!HIGHLIGHT_COLOUR.Value) & StrDup(6-LEN(hex(Fields!HIGHLIGHT_COLOUR.Value)),"0"))

Is working for me as an expression in font colour

To convert Hex strings to INT, I have used this in the past. It can be modified to convert any base to INT in fact (Octal, Binary, whatever)

Declare @Str varchar(200)
Set @str = 'F000BE1A'

Declare @ndx int
Set @ndx = Len(@str)
Declare @RunningTotal  BigInt
Set @RunningTotal = 0

While @ndx > 0
Begin
	Declare @Exponent BigInt
	Set @Exponent = Len(@Str) - @ndx

	Set @RunningTotal = @RunningTotal + 

	Power(16 * 1.0, @Exponent) *
	Case Substring(@str, @ndx, 1)
		When '0' then 0
		When '1' then 1
		When '2' then 2 
		When '3' then 3
		When '4' then 4
		When '5' then 5
		When '6' then 6
		When '7' then 7
		When '8' then 8
		When '9' then 9
		When 'A' then 10
		When 'B' then 11
		When 'C' then 12
		When 'D' then 13
		When 'E' then 14
		When 'F' then 15
	End
	Set @ndx = @ndx - 1
End

Print @RunningTotal

Below are two functions: dbo.HexToInt and dbo.IntToHex, I use them for such conversion:

if OBJECT_ID('dbo.HexToInt') is not null
	drop function dbo.HexToInt
GO
create function dbo.HexToInt (@chars varchar(max))
returns int
begin
	declare @char varchar(1), @len int, @i int, @r int, @tmp int, @pow int
	set @chars = RTRIM(LTRIM(@chars))
	set @len = LEN(@chars)
	set @i = 1
	set @r = 0
	while @i <= @len
	begin
		set @pow = @len - @i
		set @char = SUBSTRING(@chars, @i, 1)
		if @char = '0'
			set @tmp = 0
		else if @char = '1'
			set @tmp = 1
		else if @char = '2'
			set @tmp = 2
		else if @char = '3'
			set @tmp = 3
		else if @char = '4'
			set @tmp = 4
		else if @char = '5'
			set @tmp = 5
		else if @char = '6'
			set @tmp = 6
		else if @char = '7'
			set @tmp = 7
		else if @char = '8'
			set @tmp = 8
		else if @char = '9'
			set @tmp = 9
		else if @char = 'A'
			set @tmp = 10
		else if @char = 'B'
			set @tmp = 11
		else if @char = 'C'
			set @tmp = 12
		else if @char = 'D'
			set @tmp = 13
		else if @char = 'E'
			set @tmp = 14
		else if @char = 'F'
			set @tmp = 15
		set @r = @r + @tmp * POWER(16,@pow)
		set @i = @i + 1		
	end
	return @r
end

And the second one:

if OBJECT_ID('dbo.IntToHex') is not null
	drop function dbo.IntToHex
GO
create function dbo.IntToHex (@val int)
returns varchar(max)
begin
	declare @r varchar(max), @tmp int, @v1 int, @v2 int, @char varchar(1)
	set @tmp = @val
	set @r = ''
	while 1=1
	begin
		set @v1 = @tmp / 16
		set @v2 = @tmp % 16
		if @v2 = 0
			set @char = '0'
		else if @v2 = 1
			set @char = '1'
		else if @v2 = 2
			set @char = '2'
		else if @v2 = 3
			set @char = '3'
		else if @v2 = 4
			set @char = '4'
		else if @v2 = 5
			set @char = '5'
		else if @v2 = 6
			set @char = '6'
		else if @v2 = 7
			set @char = '7'
		else if @v2 = 8
			set @char = '8'
		else if @v2 = 9
			set @char = '9'
		else if @v2 = 10
			set @char = 'A'
		else if @v2 = 11
			set @char = 'B'
		else if @v2 = 12
			set @char = 'C'
		else if @v2 = 13
			set @char = 'D'
		else if @v2 = 14
			set @char = 'E'
		else if @v2 = 15
			set @char = 'F'
		set @tmp = @v1 
		set @r = @char + @r
		if @tmp = 0
			break
	end
	return @r
end