SQL Hashbytes command Output

Question

Why in SQL Server does the Hashbytes command return different responses in the following codes?

Declare @Pass nvarchar
set @Pass='SampleHash'
Select HASHBYTES('MD5',@Pass)
Select HASHBYTES('MD5','SampleHash')

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0x6F0AC8C187CEDB835A9BA373603BDA3F

0xC205AF5CE2048FF5C8C9A5B5ABDAF64E
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You declared @Pass to be a single unicode character. And your literal is an ascii string of 10 characters. Jacob posted the correct version without spelling out the biggest mistake - a single character string. — SMor, Jan 26 '18 at 14:27
@SMor Yeah I changed the type automatically without even thinking because declaring any character type in sql without a length gives me the creeps. Edited to include that information. — Jacob H, Jan 26 '18 at 14:29

Jacob H · Answer 1 · 2018-01-26T14:30:36.157

By declaring your string as unicode you will get the same HASHBYTES result:

Declare @Pass nvarchar(10)
set @Pass='SampleHash'
Select HASHBYTES('MD5',@Pass)
Select HASHBYTES('MD5',N'SampleHash')

0xB8F6457C129AEBCBB0D2E3097336ED1C

Or by using varchar instead of nvarchar:

Declare @Pass varchar(10)
set @Pass='SampleHash'
Select HASHBYTES('MD5',@Pass)
Select HASHBYTES('MD5','SampleHash')

0xC205AF5CE2048FF5C8C9A5B5ABDAF64E

Edit: Note that I have also explicitly declared the lengths of the string values as nvarchar(10) or varchar(10) to match the length of the string SampleHash.

SQL Hashbytes command Output

1 Answers1