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Updating Table Column with Random Passwords

Posted on 2008-09-29
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Last Modified: 2010-04-21
I have a stored Procedure that generates random passwords. I have a user table with a password column. Some users have Null or Empty password fields. I would like to write a script that fills these empty or NULL fields with a randomly generated password from the stored procedure
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Question by:greatseats
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8 Comments
 
LVL 60

Accepted Solution

by:
Kevin Cross earned 250 total points
ID: 22601369
Could you change to a user defined function?

If so, then you can call like this:
UPDATE users
SET password = dbo.fn_GetRandomPassword()
WHERE IsNull(password, '') = ''

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LVL 60

Expert Comment

by:Kevin Cross
ID: 22601394
Or if you are doing this in the stored procedure, you can take an approach something like this.
DECLARE @userid int -- whatever your identity column type is
 
WHILE EXISTS (SELECT 1 FROM users WHERE IsNull(password, '') = '')
BEGIN
    -- grab next user to work on
    SELECT TOP 1 @userid = userid FROM users WHERE IsNull(password, '') = ''
    -- use your logic you already have for password here
 
    -- update this user
    UPDATE users
    SET password = @password -- set to password you have already calc
    WHERE userid = @userid
END

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LVL 30

Expert Comment

by:nmcdermaid
ID: 22601407
Assuming the SP returns the password as an output parameter, something like this will do it.
Alternatively you coudl load up a table with passwords generated by your SP and then apply them.
 

DECLARE @Password VARCHAR(100)
DECLARE @UserName VARCHAR(100)
 
SELECT @UserName = TOP 1 UserNameColumn FROM YourTable WHERE PasswordColumn IS NULL -- seed the loop
 
WHILE @UserName IS NOT NULL
BEGIN
 
  EXEC p_YourProcedure @Password OUTPUT  -- get the next random password
  
  -- Apply the password (assuming UserNameColumn is unique)
  UPDATE YourTable 
  SET PasswordColumn = @Password
  WHERE UserNameColumn = @UserName
 
  SELECT @UserName = TOP 1 UserNameColumn FROM YourTable WHERE PasswordColumn IS NULL
END

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Author Comment

by:greatseats
ID: 22601555
I get the following error when i try to execute this script.

Msg 156, Level 15, State 1, Line 4
Incorrect syntax near the keyword 'TOP'.
Msg 156, Level 15, State 1, Line 16
Incorrect syntax near the keyword 'TOP'.

do you know what this is about ?


DECLARE @Password VARCHAR(100)
DECLARE @UserName VARCHAR(100)
 
SELECT @UserName = TOP 1 UserNameColumn FROM YourTable WHERE PasswordColumn IS NULL -- seed the loop
 
WHILE @UserName IS NOT NULL
BEGIN
 
  EXEC p_YourProcedure @Password OUTPUT  -- get the next random password
  
  -- Apply the password (assuming UserNameColumn is unique)
  UPDATE YourTable 
  SET PasswordColumn = @Password
  WHERE UserNameColumn = @UserName
 
  SELECT @UserName = TOP 1 UserNameColumn FROM YourTable WHERE PasswordColumn IS NULL
END

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LVL 60

Expert Comment

by:Kevin Cross
ID: 22601563
It has to be like in my comment.
SELECT TOP 1 @userid = userid FROM users WHERE IsNull(password, '') = ''

The TOP 1 must come before the assignment to variable.
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LVL 60

Expert Comment

by:Kevin Cross
ID: 22601589
Here is a blend of the approaches since you liked that one.  Since you said password can be empty or NULL I would also change to my approach of comparing to empty string after changing nulls to '' that way you catch both.
DECLARE @Password VARCHAR(100)
DECLARE @UserName VARCHAR(100)
 
SELECT TOP 1 @UserName = UserNameColumn FROM YourTable WHERE IsNull(PasswordColumn, '') = ''
 
WHILE @UserName IS NOT NULL
BEGIN
   EXEC p_YourProcedure @Password OUTPUT  -- get the next random password
  
  -- Apply the password (assuming UserNameColumn is unique)
  UPDATE YourTable 
  SET PasswordColumn = @Password
  WHERE UserNameColumn = @UserName
 
  -- grab next username
  SELECT TOP 1 @UserName = UserNameColumn FROM YourTable WHERE IsNull(PasswordColumn, '') = ''
END

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LVL 30

Expert Comment

by:nmcdermaid
ID: 22602930
Sorry I got the TOP 1 around the wrong way. Its not needed anyway.
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Author Closing Comment

by:greatseats
ID: 31501395
I really like this UDF approach, fast, clean and simple - well I had to learn more about UDF and how to create a udf password generator :-) - fun ! I am still trying to get the other SP approaches to work - running into a few issues - Thanks  very much for the assistance
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