Add a column to db-tables

I a couple of tables and have to add another Column to the existing table, and then save the table with the new Column, how do I do that, btw I'm using Delphi 2.0.
kogerAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

jturpinCommented:
The best way to do that is by using the
"Borland Database Desktop" under "Tools"
(I think) on the main Delphi2 menu.

John.
0
kogerAuthor Commented:
Ehh, well, I need to create a program that can add a column, so what I need is some code ;-)
0
jturpinCommented:
Ok you seem to have missed that point in
your original question.

I don't believe you can simply add a column
to a table. I usually clone the structure
of the original table, add the column, and then
select the info I need. But you could try
simply adding the column to the existing table
if you want, although I think you will get
an error.

The code for adding a column to the table is:

   OriginalTable.FieldDefs.Add(FieldName,
      FieldType,FieldLen,false);

   e.g.
      Table1.FieldDefs.Add('SupCarry',ftString,SupLEN,false);
      Table1.FieldDefs.Add('PayCarAll',ftBoolean,0,false);
      Table1.FieldDefs.Add('Rate',ftFloat,0,false);
      Table1.Exclusive:= true;
   
      Table1.CreateTable;

I hope that helps,

John.
0
Cloud Class® Course: Microsoft Windows 7 Basic

This introductory course to Windows 7 environment will teach you about working with the Windows operating system. You will learn about basic functions including start menu; the desktop; managing files, folders, and libraries.

kogerAuthor Commented:
To jturpin

Here is a ex. of the code I use:

Table1.FieldDefs.Add('NewEntry:', ftString, 25, False);
Table1.CreateTable;

This will causs all the existing information in the table to be erased :-(, how is it possible to keep the existing information and still add an extra column?
0
ronit051397Commented:
Use SQL. For adding a new field, called 'TEST' to the ANIMALS table write:

with Query1 do
begin
  DatabaseName:='DBDEMOS';
  SQL.Text:='ALTER TABLE "ANIMALS.dbf" ADD TEST SMALLINT';
  ExecSQL;
end;

0
kogerAuthor Commented:
It must be possible to add a column, without using SQL.
0
BlackManCommented:
You need to use the dbiDoRestructor procedure. There is an example at http://www.inprise.com/devsupport/bde/bdeapiex/dbidorestructure.html
0
kogerAuthor Commented:
Ok I have tried it all, and I simply don't get it, so I will take it one more time

I have to add a column to a paradox table, I need some code for Delphi 2.0 that does the trick.

The existing columns was made with fielddefs

with Table1.FieldDefs do
begin
  Clear;
  Add('Column1', ftString, 50, False);
  Add('Column2', ftString, 50, False);
end;
Table1.CreateTable;

if I try to add another column after table1.createtable was used,
I get an error.

Table1.FieldDefs.Add('Field3', ftString, 25, False);
Table1.FieldDefs.Update;
DBEdit3.DataField := 'Field3';  <-- error 'Field3 dosn't exist!'

If I call Table1.CreateTable again the whole table will be erased, all the information written in the table are lost.

Would someone give me an example that matches my table?
0
ronit051397Commented:
What's wrong with SQL?
0
MarciusCommented:
The use of fielddefs will not create a row in the underlying table. It is an operator designed to manipulate TDataset, not the underlying table.

I really think that the best solution is to use SQL. Other than that, you can re-create a new table each time you want to add a column, migrate the data, then destroy the old table. As you can see, SQL is the cleaner option.
0
kogerAuthor Commented:
Ok, how do I use SQL?
0
ronit051397Commented:
I have already posted the answer on SQL and you rejected it.
0
kogerAuthor Commented:
To Ronit.

The reason that I really didn't want(ed) to use SQL, is that my application don't use SQL and I haven't used SQL before.

you gave me this SQL statement,

  SQL.Text:='ALTER TABLE "ANIMALS.dbf" ADD TEST SMALLINT';

I need a string field with the length 25, I haven't got any manual that covers SQL statements, so it is a bit tricky to figure out how the statement should look, will help me with that?
0
ronit051397Commented:
This must be done exclusively, meaning the table cannot be active in your application or another application, while SQL is executing:

with Query1 do
begin
    DatabaseName:='DBDEMOS';
    SQL.Text:='ALTER TABLE "ANIMALS.dbf" ADD TEST CHAR(25)';
    ExecSQL;
 end;

for more information on SQL statements see:
C:\Program Files\Borland\Common Files\BDE\Localsql.hlp
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
kogerAuthor Commented:
Thanx!!
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Delphi

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.