March 19, 1997

Adding and Removing Columns from Tables

Question: How can I add and remove columns from a table at run time? Answer: While I’m an avid supporter of Delphi, one of the most annoying things about it is its lack of table management routines for local tables such as Paradox or dBase tables. Specifically, the ability to

How do I set Paradox table passwords?

Question: How can I set Paradox table passwords in Delphi 2.0? Answer: Let Me Blow Off Some Steam About the BDEUnfortunately, setting passwords on Paradox tables cannot be done using native Delphi calls. You have to use Borland Database Engine (BDE) calls. I’ve written a few examples of making BDE

Accessing a C Library from Java Applet

Question: I want to be able use a Web frontend for a databaseapplication. I would like to use Java to process theuser input and C for accessing the database. Myquestion is: Is there any way I can access a dynamically linked library written in C from a Java applet? Bothclient

What is an Interface?

Question: I have no experience with object-oriented languages, havingonly learned BASIC when I was a child. Most people say Java is easy,but in my case it’s not. I don’t understand the keyword ‘implements’, Idon’t understand ‘interface’. Is there anydifference between a class and aninterface? Without an interface, are there any

Too many TDBEdit components on a Form

Question: I am using Delphi 16 running under Win95.I have an application which requires use of more than 200 TDBEdit components. When designing the form I find that 178 appears to be the max allowed. Once this figure is reached no more TDBEdit or TEdit components may be added. The

What does the message “file not found math.pas” mean?

Question: I can not use tha math functions which was included in math unit. when I use one of them , the compiler cant identify it. I add ‘math’ to uses clause. but this time I get a message file not found math.pas. Answer: First of all, if you read

How can I properly use CreateProcess to instantiate a new process?

Question: Here is the code I’m using (the error is posted where it occurs):=================================TypePROCESS_INFORMATION = record hProcess: Longint; hThread: Longint; dwProcessID: Longint; dwThreadID: Longint;End;Procedure ExecCmd(cmdline: String);varprocc: PROCESS_INFORMATION;startup: TSTARTUPINFO;ret1: longint;ret2: longint;ret3: longbool;Const NORMAL_PRIORITY_CLASS = $20;Const INFINITE = -1; Begin startup.cb:= SizeOf(startup); ret1:= CreateProcess( nil, PChar(cmdline), nil, nil, LongBool(1), NORMAL_PRIORITY_CLASS, nil, nil,

What is the best way to update a date field every time a record is posted?

Question: When I add the code ‘update.text := dateToStr(Date)’ toOnUpdateChange of the DataSource, it works some of the time. Forexample, if the record is posted by moving to another record, theupdate works fine. If it is posted by clicking the post button (fromdataNavigator component), the update does not work. Any

Incremental Searches with a TListbox

Question: How can I create a form that has a list box that I can perform an incremental search on? Answer: There are a couple of ways to do this. One’s hard and slow, the other easy and fast (we’re going to take the easy and fast option). For those

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