How use EPQDatabaseError ?
lazarus / 16-Databases

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Pabdym · 2012-10-08 09:05

Hi,

I look for examples of use of EPQDatabaseError.SQLState
(TPQConnection) with SQLquery.ExecSQL (INSERT, UPDATE, DELETE)  and
SQLquery.Open (SELECT... FOR UPDATE NOWAIT).

Thanks.

PS : TSQLTransaction.Action := caCommit;  All other properties of
TPQConnection, TSQLTransaction, TSQLQuery : by default.

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Pabdym · 2012-10-10 14:33

After many tests, I was easily able to obtain with the
EQPDatabaseError, the codes of errors corresponding to errors of
formulation in the requests. But, never, for example, I have to make
send back : Code of error 23505 ( unique_violation ) in an Insert or
UpdateSQL while E.message ( EDataBaseError) indicates correctly the
violation.

It seem's that it is not possible. It is really a lack if we compare
with the use of FIBConnection.

Regards.

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ludob · 2012-10-10 17:21

There are some parts of pqconnection that still use EDatabaseError
instead of the extended EQPDatabaseError. As a result you get extended
info for the preparation of the query (syntax errors, etc) but not for
the execute part (unique violation,...). I'll create a fix for that.

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ludob · 2012-10-10 18:43

A fix is committed to FPC 2.7.1 rev 22610. A EPQDatabaseError is now
raised for execute. There is still a mix of EPQDatabaseError and
EDatabaseError because the first one is only relevant for result sets.
So your code should look like the following test snippet:

Code: [Select]    SQLQuery1.SQL.Text:='create table testunique (id
integer NOT NULL, CONSTRAINT "PK_testunique_id" PRIMARY KEY (id ))';
    SQLQuery1.ExecSQL;
    SQLQuery1.SQL.Text:='insert into testunique values (1)';
    SQLQuery1.ExecSQL;
    try
      SQLQuery1.SQL.Text:='insert into testunique values (1)';
      SQLQuery1.ExecSQL;
    except
      on E: Exception do
        if E is EPQDatabaseError then
          Showmessage((E as EPQDatabaseError).SQLSTATE);
    end;
The test will pop up a box with '23505'.

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Pabdym · 2012-10-10 18:49

OK. Thank you.

If I can help : I have the possibility to test the code:
Lazarus/FPC trunk  Win, Linux (32 and 64 bits), MACPostgreSQL9.1
Servers Win 32and Squeeze 64.Regards.

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Pabdym · 2012-10-10 22:49

Client -->  Win32:  fpc/trunk -Rev. 22610 - laz/trunk-Rev. 39038
Server -> Squeeze 64 bits - PostgreSQL 9.1.5
Tested with an Insert Request : It works fine.
Look at the attachment please. 

Question : To install Lazarus/FPC, I respected the procedure described
in the link (by replacing 2.6.1 by trunk) http://wiki.freepascal.org/I
nstalling_Lazarus#Compiling.2Finstalling_FPC_and_Lazarus_from_Sources_
of_SVN_.28Win32.29

It works correctly but at the end, it is necessary to add missing
files in \lazarus\fpc\trunk\bin\i386-win32 : make.exe and gdb.exe. Is
it normal ?

Thank you again for your help.
Regards.

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ludob · 2012-10-11 06:27

QuoteIt works correctly but at the end, it is necessary to add missing
files in \lazarus\fpc\trunk\bin\i386-win32 : make.exe and gdb.exe. Is
it normal ?To build trunk you need a 2.6.0 compiler which typically
comes with make.exe. It is not necessary to re-install as long as it
can be found in the PATH. For lazarus in Tools/Setup/Environment you
can set the path tp make.exe. In Tools/Setup/Debugger you can set the
path to gdb.exe.