On top of this is the AutoCommit flag. Yes, I have read the quick guide in documentation area which has a brief explaination about it and has 4 URLs linking to 4 relative threads, but after I want over them, I was still hard to understand how to use it in a correcting way.
In fact, my problem is, my autocommit was set to true, and I used multithread to achieve the purpose, that was every threads could update or select data from a FB database file and they shared a TZConnection, but they had different TZQuery in their thread.
Sometimes they ran well, but sometimes, an exception raised from my program as below:
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Project XXX.exe raised exception class EZDatabaseError with message 'Invalid operation in AutoCommit mode'. Process stopped. Use Step or Run to continue.
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Here is the 'update' clauses.
Code: Select all
try
fdbquery.SQL.Clear();
fdbquery.Close();
fdbquery.Connection.StartTransaction();
fdbquery.SQL.Add(sqlstr);
fdbquery.ExecSQL();
fdbquery.Connection.Commit();
fdbquery.Close();
except
if fdbquery <> nil then begin
fdbquery.Connection.Rollback();
fdbquery.Close();
end;
end;
Code: Select all
try
fdbquery.SQL.Clear();
fdbquery.Close();
fdbquery.Connection.StartTransaction;
fdbquery.SQL.Add(sqlstr);
fdbquery.Open;
while not fdbquery.Eof do begin
{ fetch data }
fdbquery.Next();
end;
fdbquery.Connection.Commit;
fdbquery.Close();
except
if fdbquery <> nil then begin
fdbquery.Connection.Rollback;
fdbquery.Close();
end;
Result := false;
exit;
end;
Here is the process opening the database.
Code: Select all
fdb := TZConnection.Create(nil);
if not FileExists(fdbfullname) then begin
if not inCreateDB(fdbfullname, fdbdllfullname) then begin
Result := false;
exit;
end;
end;
fdb.Disconnect;
fdb.Database := fdbfullname;
fdb.User := 'SYSDBA';
fdb.Password := 'masterkey';
fdb.Protocol := 'firebirdd-2.0';
fdb.Properties.Clear;
fdb.Properties.Add('Dialect=3');
fdb.Properties.Add('hard_commit=yes');
fdb.Connect;
Code: Select all
sqlstr := Format('CreateNewDatabase=CREATE DATABASE ''%s'' USER ''SYSDBA'' PASSWORD ''masterkey'' PAGE_SIZE 16384 DEFAULT CHARACTER SET NONE', [dbfullname]);
fdb.Properties.Clear;
fdb.Properties.Add(sqlstr);
fdb.Properties.Add('Dialect=3');
fdb.Properties.Add('hard_commit=yes');
fdb.Database := dbfullname;
fdb.Protocol := 'firebirdd-2.0';
fdb.TransactIsolationLevel := tiReadCommitted;
try
fdb.Connect;
except
Result := false;
exit;
end;
try
try
sc := TZSQLProcessor.Create(nil);
except
Result := false;
exit;
end;
sc.Connection := fdb;
sc.DelimiterType := dtSetTerm;
fdb.StartTransaction;
{something about sc.Script.Add(...) }
try
sc.Execute;
except
fdb.Rollback;
Result := false;
exit;
end;
fdb.Commit;
Result := true;
finally
if sc <> nil then begin
sc.Connection := nil;
FreeAndNil(sc);
end;
end;
