Question

I need to execute this Sql command (which works fine in management studio):

select * from Users where Login = 'test' and PasswordHash = HashBytes('SHA1', 'test')

I wrote this c# linqtosql:

var user = db.ExecuteQuery<User>("select * from Users where Login = {0} and PasswordHash = HashBytes('SHA1', {1})", loginTextBox.Text.Trim(), passwordPasswordBox.Password).SingleOrDefault();

but it never works!!

can anybody help me?

thanks!

This is the DataContext’s log:

select * from Users where Login = @p0 and PasswordHash = HashBytes('SHA1', @p1)
-- @p0: Input NVarChar (Size = 4000; Prec = 0; Scale = 0) [test]
-- @p1: Input NVarChar (Size = 4000; Prec = 0; Scale = 0) [test]
-- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 4.0.30319.1

Answer 1

I profiled it via db.Log = Console.Out, with the result:

-- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 4.0.30319.1

select * from Users where Login = @p0 and PasswordHash = HashBytes('SHA1', @p1)
-- @p0: Input NVarChar (Size = 4000; Prec = 0; Scale = 0) [Admiral Trask]
-- @p1: Input NVarChar (Size = 4000; Prec = 0; Scale = 0) [Arutha]
-- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 4.0.30319.1

Looking at this, I imagine the problem is that the param is NVarChar rather than varchar – so taking the hash (a binary operation) is different. If you hashed it as varchar, you should probably cast the string to varchar before the HASHBYTES.

The following works, for example:

var user = db.ExecuteQuery<User>(@"select * from Users where Login = {0}
        and PasswordHash = HashBytes('SHA1', CAST({1} as varchar(40)))", cn, pw)
        .SingleOrDefault();

A simpler illustration of this is:

SELECT HASHBYTES('SHA1','12345'), HASHBYTES('SHA1',N'12345')