Inserting a hashbyte value into a table via stored procedure - sql-server

Question

I have created a table with username,password,hashvalue as columns.
create table userDetails
(
username varchar(50),
password varchar (50),
hashvalue varchar (3000)
)
I want to have each password stored in the table to be hashed by executing a stored procedure and in the same stored procedure, the hashed value is inserted into the table.
I created the stored procedure as follows :
CREATE PROCEDURE hashpwd
#username varchar(50) = default ,
#pwd varchar(50) = default
AS
BEGIN
DECLARE #hashed varchar(4000);
SET #hashed = HASHBYTES('SHA1', #pwd); --edited to #pwd
select username,password from userDetails
WHERE username LIKE #username AND password LIKE #pwd;
END
BEGIN
insert into userDetails
(hashvalue) values (#hashed);
END
The procedure can be executed, but the result is wrong. It produces NULL and a random string of characters. A 3rd row was also created when there are only 2 rows in the table initially.
Any guidance is appreciated.

Answer 1

Create PROCEDURE hashpwd
#username varchar(50) = default ,
#pwd varchar(50) = default
AS
BEGIN
DECLARE #hashed varchar(4000);
SET #hashed = HASHBYTES('SHA1', #pwd); --(#pwd instead of #hashed)
Update userDetails set hashvalue = #hashed
WHERE username LIKE #username AND password LIKE #pwd
END
You should use Update statement instead of Insert and statement should appear with in the procedure body.

Answer 2

I keep getting an error when submitting my response, but for the previous response above, replace the where clause with this
WHERE username = #username

Answer 3

The reason you are seeing the wrong results is due to the data type for your hashvalue column. As the HASHBYTES function returns VARBINARY, you should use this as your data type.
create table userDetails
(
username varchar(50),
password varchar (50),
hashvalue varbinary(40) -- Note, this should only be 40 characters long
)
I'm not really sure what youre stored procedure is meant to do. I would imagine that for a given username & password, you want to update the hashvalue on the corresponding row? If so, I would do this.
CREATE PROCEDURE hashpwd
#username varchar(50) = default ,
#pwd varchar(50) = default
AS
BEGIN
UPDATE userDetails
SET hashvalue = HASHBYTES('SHA1', #pwd); --edited to #pwd
WHERE username LIKE #username AND password LIKE #pwd;
END