Delphi, Authentication from database

Question

I am planing to include authentication capabilities in my program.

I need information about switching between table records. My current program is only reading the username and password from the first record.

How do I move to subsequent table records?

problem is in that how to make programm switch to next record if current records usern. and pasw. checking fails — user2481841
– user2481841, Commented Jun 13, 2013 at 12:11
You should look up the TDataSet.Locate method. It moves the record to matching criteria, and returns false if the record is not found — Anya Shenanigans
– Anya Shenanigans, Commented Jun 13, 2013 at 12:14
Hmm, i realy dont know what are u talking about. Im comparing authentications forms edit.text fields with DBedit.text fields... If you would say what code rows should be added, that would be great, ty! !! — user2481841
– user2481841, Commented Jun 13, 2013 at 12:23
If your database supports SQL it could be easier to execute a SQL SELECT COUNT(*) FROM USERTABLE WHERE <username>=:param1 and <password>=:param2 statement - instead of navigating through a dataset — mjn
– mjn, Commented Jun 16, 2013 at 20:01

Ken White · Accepted Answer · 2013-06-13 12:56:20Z

1

Just use TDataSet.Locate. In all of the below, I'm using ds to represent your TDataSet variable.

UserName := EditUserName.Text;
Password := EditPassword.Text;
if ds.Locate(UserName, ['UserNameField']) then
begin
  if ds.FieldByName('Password').AsString = Password then
    // Passwords match
  else
    // Passwords don't match
end
else
  // User name not found

To move from one record (row) to the next, simply use ds.Next;, and to move to the one before use ds.Prior;. To go to the first row, use ds.First, and ds.Last to go to the last one.

This is really basic database programming. You should probably search for a tutorial that explains it and work through it.

answered Jun 13, 2013 at 12:56

Ken White

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Ali Avcı · Accepted Answer · 2013-06-13 12:25:48Z

1

Dataset has a Next method, that way you may traverse the whole dataset.

qDS.Open ; 
while not qDS.EOF do
begin
   anyString := qDS.fieldbyname('usern').asString ; // will give you the username
   qDS.Next ; // go to the next record in the dataset.
end ;
qDS.close ;

answered Jun 13, 2013 at 12:25

Ali Avcı

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