创建自己的数据库

type

   TMember = record

     Name : string[50];

     eMail : string[30];

     Posts : LongInt;

   end;

 

  var Members : array[1..50] of TMember;

 

var F : file of TMember;

 

write data

var

   F : file of TMember;

   i : integer;

 begin

  AssignFile(F,'members.dat') ;

  Rewrite(F) ;

  try

   for j:= 1 to 50 do

    Write (F, Members[j]) ;

  finally

   CloseFile(F) ;

  end;

 end;

read data

var

   Member: TMember

   F : file of TMember;

 begin

  AssignFile(F,'members.dat') ;

  Reset(F) ;

  try

   while not Eof(F) do begin

    Read (F, Member) ;

    {DoSomethingWithMember;}

   end;

  finally

   CloseFile(F) ;

  end;

 end;

 

seek and position

{go back to the beginning - the first record}

 Seek(F, 0) ;

 

 {go to the 5-th record}

 Seek(F, 5) ;

 

 {Jump to the end - "after" the last record}

 Seek(F, FileSize(F)) ;

 

change and update

procedure ChangeEMail(const RecN : integer; const NewEMail : string) ;

 var DummyMember : TMember;

 begin

  {assign, open, exception handling block}

  Seek(F, RecN) ;

  Read(F, DummyMember) ;

  DummyMember.Email := NewEMail;

  {read moves to the next record, we have to

  go back to the original record, then write}

  Seek(F, RecN) ;

  Write(F, DummyMember) ;

  {close file}

 end;