This is a short document describing dsTable. By reading this document you should get a better understanding of what dsTable is and what it can do.
You can test this demo on
Access, Firebird, MySQL, Pervasive SQLite or VistaDB database. Databases are already
there for Access and Firebird. For MySQL, you will need to create a database with name
TeamSupport. For Pervasive you need to create folder with name DBBTRV in the
application folder. For SQLite you will need sqlite3.dll on the same folder as
exe is. After that just set the right parameters in TeamSupport.ini and you are ready to
Start the demo application. You should see one MDI form already on the screen. That is events form. Letís say event is everything that can occur in a company. A phone call, idea, something to do, etc. We will only use here few of them as a demo.
fill some demo data, select Actions|Insert test data and press refresh on the
start by showing some simple things, yet powerful. Select columns button on
the events form to setup columns for events table.
select Name of the Client and Name of the Zip as shown on the picture and
should see lookup fields in the grid now. They have a small blue dot in the
column header showing that those are lookup columns.
We will see that later on.
now Data|Customers. Set windows like those on the picture above to see events
form in the background and select edit button (F9 shortcut). Edit the record,
change the name of the client and press post button (F10 shortcut). Notice how
things are refreshed even in events form.
relationships, the story is similar. You define some properties on the fields
that can have lookups behind and if you change the ClientID, dsTable generates
tasks that should be done to change old ClientID in all the tables that
includes that ClientID. Or records can be deleted or left as they are. It all
depends on the property you set.
already said, all things are managed from one place, that is Delphi IDE. There
can be a component editor to make comments on the table and fields. There can
even be a component editor for relationships like the one on the picture. It
is just a sample window to show you all the possibilities.
on, as things are managed from one place, even changing tables is a matter of
seconds. Adding new field for example. You donít need to change table struct
in some other application, generate sql script, run that script on the
database, go back to Delphi, add TField on TDataset and add editors. You just
add field on dsTable in Delphi and add editor on the right place, everything
else is done for you by dsTable. That means, as you start your application,
dsTable should know how to check struct and if struct is not ok, existing
table is upgraded (one way is to rename existing table, create new table and
copy all the data to the new table).
uses dsDatabase to connect to any database desired. The functionality of
dsDatabase is slightly different that usual databases in Delphi. You write
your own dsDatabase by using standard components for access like TQuery,
TTable, TADOQuery, TmySQLQuery, etc. The use of those components is very
similar so new dsDatabases should be written quite quickly.
see now some other things that dsTable supports. First of all, rights. You
define rights on dsTable and dsFields. That means you can define whether user
can insert, edit or delete records and you can define whether user can see or
edit individual fields.
Try|Select rights to set some rights. Then you can select Data|Zip and you
should not see Name column in the grid or in the columns setup. Further on you
should not be able to delete records and if you edit one of the events in the
events form by pressing F9, you should see field (editor) Author read only, so
you canít edit it.
Next thing are colors. You use dsColors to define colors and you connect dsTable with dsColors and write OnGetGridDrawData. From that point, every table will know how to color rows in the grid. You can see that in events form. Even drop down grid in edits will show the right color as it asks dsTable for the color.
Open Data|List2 to see how LookupFilter is used dinamicly on Person field. You'll have to select customer first to see persons that belong to some customer. If you look at the sources, you will see that this filter is assigned in datamodule as OnGetLookup event for field Person on table List2. Notice how this is only done once and it will be used on all tables that are of struct List2, that is, on all tables that List2 struct is assigned.
Additionaly you will notice how Persons don't have form to edit them. That makes Persons as a non editable table, but you can still select from that table if you press lookup button on some field. Persons will be shown in default form. This is the code:
GlobalLookupForm := TGridForm;
GlobalLookupForm is variable in dsTable unit. It is used for all tables that don't have LookupForm assigned. For some other tables, lookup forms are assigned like this:
that are used here are derived from standard DB controls. They have some more
code behind to be able to work with dsTable. Nothing much.
if Datasource.Dataset.Owner is TdsTable then...
Some nice things about editors. Edit knows how to locate lookup fields and how to show lookup form or drop down grid. When validation is called it knows what to validate, uses colors and hint to show what is wrong (try to insert empty record into Zip table to see validation). DBEdit gets it's values from dsField as for Edits, you can call SetEditFromField. That brings many good things with it as you only need for example to define allowed values once, in dsField with script for example, after that all edits will use that.
Notice how things get filtered with this grid. Just put cursor into right column and start to type. If field is of type string, every character will narrow your choice. If field is integer for example, you will get a quick filter dialog to enter values from and to. Or if you are on the field that has lookup behind, press Ctrl+Space to get quick filter form and notice how this edit already knows some things about lookup. That is all possible because you ask dsTable some things and then you know how to setup things to work perfect.
Now letís get back to Table.FieldByName(ĎClient.Zipí).AsString. In the events form select special (that little hammer) and design report. Select File|Open and open Report01.rpt. Select Client.Zip.Name field. That is TdsrDBText and this is the way, how to get any field to report that is somehow connected with this table trough lookups. No need for programmer to write SQL joins. Perhaps you should close designer now and select print in events form. Find that report again and press ok too see how things are printed.
is ment for small to middle size applications where speed of development and
changing applications is essential even if speed of applications and size is
sometimes put aside. Size is not a problem these days any more and with faster
and faster machines, speed of applications is not so important as before. At
the moment I'm working and testing next dsDatabases. Access via TADOQuery,
Pervasive vis TBTRVTable, VistaDB via TVDBTable, Firebird via TIBOQuery in
MySQL via TmySQLQuery.
are even more things that can be done but this is just a small demo to present
things. Iím in fact looking for interested people or companies to develop
things further on.