Problems connecting to Firebird #2
lazarus / 16-Databases

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emaza · 2008-03-20 04:09

Hi. I really need help.

I am new to Firebird and Lazarus (and to RADtools, OOP and to “real
mission-critical, not toy-desktop-databases”, etc). To teach myself
before starting a real project –not an easy task- I tried building a
simple one-form program, to build and edit a list of accounts using my
Windows XPpro laptop as both sever and client. I installed the
Superserver version 2.0.3 as a service, and (I think) the FBCLIENT.dll
and not the GDS32.dll, since I understood this to be the preferable
choice, for those with no “legacy” issues.

I Used Firebird’s ISQL tool to build a database (Test.fb, not “.fdb”
because it was what the TIBConnection seemed to like when searching
for a database to link) with two tables. Table1 with Two columns:
Acct_No and Acct_Descrip; and a Table2 with an additional column using
Firebird’s Generator feature to create an “autonumeric” ID column.
This in case it was needed by Lazarus’ Navigator buttons.

From the SQLdb tab I dropped boxes on the form: TIBConnection,
TSQLQueery and TSQLTransaction. Wrote a “SELECT * FROM.. (table)”
command on the TSQLQueery. Connected everything and also dropped a
TDBGrid, a TDBNavigator and a TDBEdit, this last to leave the grid as
read-only. Everything works fine as far as moving the pointer,
editing, inserting, and deleting rows in the DataSet of either table,
as displayed by the grid, but changing any data inside either of the
two tables is, however, impossible.

I have spent weeks reading everything I could find in the Firebird’s
and Lazarus’s documentations, wikis, and everything I could Google. It
helped to get me this far, but no further. I have tried everything I
could think of, and/or copy, from the little information available,
and have only produced errors or access violations. I am ready to give
up.

This is a last resort request. If someone out there could point me to
a reference, example, white-paper, web-page, book, or any resource
that could help me with this, it would be great. Do not want to go
back to Dbase tables, and last century’s DOS Foxbase programming.

Help!   :roll:  :evil:  :?

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tatamata · 2008-03-20 10:12

Hello.
Have you checked Read-only property of datasets and controls?
I use Zeoslib with Firebird 2.0.3 and works perfectly well, so I would
suggest you to give it a try. As you are a beginner, the benefit with
Zeoslib is that it behaves very much like BDE in Delphi, so you can
use any Delphi book regarding databases as well as Firebird
documentation to learn about it.
That's how I started.

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emaza · 2008-03-25 21:38

Hi! Many thanks for replying. I was out for Easter.

Yes, I have tried setting ReadOnly to False on all components,
including the TDBGrid with no results. I have also tried writing SQL
commands in the DeleteSQL, InsertSQL and UpdateSQL properties of the
SQLQuery box, but only the string in the SQL property of the SQLQuery
seems to work. (The SQLQuery box/component is from the SQLdb tab)

Following your advise I went to Zeos page –too many download options!
I downloaded release candidate version: ZEOSDBO-6.6.2-rc, since the
last labeled “stable version” I could find seemed too old, 2004 I
believe, and was unsure of what the MD5 and SHA versions meant.
Created an “installed_components” file inside the
C:\lazarus\components folder and emptied the zip there. With Lazarus,
I compiled the zcore, zparses, zplain, and zdbc Lazarus packages and
installed the zcomponent package. The Zeos Access tab is now in my
Lazarus editor with, I believe, all the needed access components, BUT,
I get a “Requested database driver was not found” error when I try to
set to “True” the Active property of  the TZQuery dropped in my form.

Searched the web for this error but found little help. Did I download
the wrong Zeoslib version, or is it something else?

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tatamata · 2008-03-26 07:51

Hi.
You don't need SelectSQL, InsertSQL or UpdateSQL for regular SQL
query. You only need regular TZQuery component for read-only queries
with it's SQL property. Those additional properties are only used with
so-called updateable queries, which is an extension to normal query
behavior. Bare in mind that normal select queries are normally always
read-only if based on more than one table (joins), even if you set
REad-only property to false. It can be updatable only if the query is
based on only one table. The purpose of queries are to retrieve
results, not to provide updateable dataset. You can make queries
consisted of several tables updatable too, by combining ZQuery and
ZUpdateSQL components (see Firebird documentation regarding Delphi),
but before you do it, ask yourself do you really need updateable
query? It is most likely that for data input regular ZTable component
is enough. Contrary to ZQuery which is read-only by defaulr,
especially if query is based on more than one table, ZTable is
updatable by default. Use ZTable for data input and update. Use ZQuery
for reporting of results. Use combination of ZQuery and ZUpdateSQL
components only in special situations, when normally read-only SQL
query must be updateable. Read Firebird documentation and Zeos
documentation to see how to do it. It is not easy, I warn you.
Regarding database driver, I suppose it is due Path environmental
variable. I suppose that the path to Firebird client libraries is not
set on your system. So, you have two options: either set the path to
Firebird client libraries in the Path environmental variable, either
download Firebird embedded and extract DLLs into your project
directory. Rename fbembed.dll to fbclient.dll or gds32.dll (I am not
sure, but think that Zeos prefers gds32.dll). Then check the following
ZConnection properties:
Database - full path to your database
Password - masterkey
Port -3050
Protocol - firebird-2.0
TransactionIsolationLevel - tiReadCommitted
User -SYSDBA
DesignConnection -true
AutoCommit -true
Connected -true
Host -localhost

Regards,

Zlatko

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emaza · 2008-03-30 23:18

Hi

Followed your instructions and fixed Zeos problem. It is embarrassing
to admit, but might help others to know error was because protocol
property on ZConnection was empty. Setting it to firebird 2.0 fixed
everything. Did not have to switch fbclient.dll to gs32.dll

Many many many many thanks Zlatko. I can now make changes to a table,
experiment and learn how to best use Z components following your
advice on ZQueries and Ztable components.

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tatamata · 2008-03-31 09:00

I'm glad you did it!
Keep on going:)

Zlatko