Delphi，来自数据库的身份验证

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?

Answer 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 ;

Answer 2

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.