Convert HashBytes to VarChar
SqlSql ServerSql Problem Overview
I want to get the MD5 Hash of a string value in SQL Server 2005. I do this with the following command:
SELECT HashBytes('MD5', 'HelloWorld')
However, this returns a VarBinary instead of a VarChar value. If I attempt to convert 0x68E109F0F40CA72A15E05CC22786F8E6 into a VarChar I get há ðô§*à\Â'†øæ instead of 68E109F0F40CA72A15E05CC22786F8E6.
Is there any SQL-based solution?
Sql Solutions
Solution 1 - Sql
I have found the solution else where:
SELECT SUBSTRING(master.dbo.fn_varbintohexstr(HashBytes('MD5', 'HelloWorld')), 3, 32)
Solution 2 - Sql
SELECT CONVERT(NVARCHAR(32),HashBytes('MD5', 'Hello World'),2)
Solution 3 - Sql
Use master.dbo.fn_varbintohexsubstring(0, HashBytes('SHA1', @input), 1, 0) instead of master.dbo.fn_varbintohexstr and then substringing the result.
In fact fn_varbintohexstr calls fn_varbintohexsubstring internally. The first argument of fn_varbintohexsubstring tells it to add 0xF as the prefix or not. fn_varbintohexstr calls fn_varbintohexsubstring with 1 as the first argument internaly.
Because you don't need 0xF, call fn_varbintohexsubstring directly.
Solution 4 - Sql
Contrary to what David Knight says, these two alternatives return the same response in MS SQL 2008:
SELECT CONVERT(VARCHAR(32),HashBytes('MD5', 'Hello World'),2)
SELECT UPPER(master.dbo.fn_varbintohexsubstring(0, HashBytes('MD5', 'Hello World'), 1, 0))
So it looks like the first one is a better choice, starting from version 2008.
Solution 5 - Sql
convert(varchar(34), HASHBYTES('MD5','Hello World'),1)
(1 for converting hexadecimal to string)
convert this to lower and remove 0x from the start of the string by substring:
substring(lower(convert(varchar(34), HASHBYTES('MD5','Hello World'),1)),3,32)
exactly the same as what we get in C# after converting bytes to string
Solution 6 - Sql
With personal experience of using the following code within a Stored Procedure which Hashed a SP Variable I can confirm, although undocumented, this combination works 100% as per my example:
@var=SUBSTRING(master.dbo.fn_varbintohexstr(HashBytes('SHA2_512', @SPvar)), 3, 128)
Solution 7 - Sql
Changing the datatype to varbinary seems to work the best for me.