Re: [sqlite] QT4 ubuntu sqlite driver problem ? (was Re: [sqlite] Weird error)

[Alain Bertrand]

John Stanton a écrit :

Alain Bertrand wrote:



In a Qt4 application, I have the following bit of code :

  QString s;
 bool b;
 QSqlQuery q;
 QSqlError err;
 s= "CREATE TABLE ttd_bdata (sheetId integer primary key,";
 s+="creation_date date, modif_date date,";
 s+="speciesId integer,USDA_zone integer,";
 s+="generalities text,propagation text,care text,";
 s+="esthetics text, phyto text,miscellaneous text)";
 //s="SELECT * FROM ttd_species WHERE speciesId=4";
 qWarning( s.toAscii() );
 b=q.exec( s );

Executing the query fails with the following information

SQL logic error or missing database
Unable to fetch row
Err number 1.





I have found the solution in the qt4 doc :
-
The driver is locked for updates while a select is executed. This may 
cause problems when using QSqlTableModel because Qt's item views fetch 
data as needed (with QSqlQuery::fetchMore() in the case of QSqlTableModel).



To avoid the problem, one may use the clear() method of the QSqlQuery.

Alain


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[sqlite] QT4 ubuntu sqlite driver problem ? (was Re: [sqlite] Weird error)

[Alain Bertrand]

Joe Wilson a écrit :

--- Alain Bertrand <[EMAIL PROTECTED]> wrote:



> --- Alain Bertrand <[EMAIL PROTECTED]> wrote:

In a Qt4 application, I have the following bit of code :

  QString s;
 bool b;
 QSqlQuery q;
 QSqlError err;
 s= "CREATE TABLE ttd_bdata (sheetId integer primary key,";
 s+="creation_date date, modif_date date,";
 s+="speciesId integer,USDA_zone integer,";
 s+="generalities text,propagation text,care text,";
 s+="esthetics text, phyto text,miscellaneous text)";
 //s="SELECT * FROM ttd_species WHERE speciesId=4";
 qWarning( s.toAscii() );
 b=q.exec( s );

Executing the query fails with the following information

SQL logic error or missing database
Unable to fetch row
Err number 1.

If the query is remplaced by the commented one, I got no error. If I open
my database file with sqliteman, the query is executed without any
problem. Some ideas ?


I don't understand your description, but here are some random thoughts
that might help you:


Thanks for your answer.


CREATE statements do not return any rows.


Yes, so why do I get this message from the qt driver ?


Your select table did not match the create statement table. Instead:

  Use "SELECT * FROM ttd_bdata WHERE speciesId=4"


This is not an error. The table is not created so the select on a table
which I know does exists is here to prove that I don't have a "missing
database" error.

To add to obscurity, if I run the same function in a different context, it
is ok but very simple queries (like UPDATE ttd_version SET minor='1' WHERE
Id=1) fails both in my app and in sqliteman.

I would now think of a QT/sqlite driver bug. Does anybody heard of some
problem with the sqlite driver in the qt4 libs of Ubuntu feisty ?




Don't use += in this case


ok.

AlainQT4



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[sqlite] Weird error

[Alain Bertrand]

Hi all
In a Qt4 application, I have the following bit of code :

 QString s;
bool b;
QSqlQuery q;
QSqlError err;
s= "CREATE TABLE ttd_bdata (sheetId integer primary key,";
s+="creation_date date, modif_date date,";
s+="speciesId integer,USDA_zone integer,";
s+="generalities text,propagation text,care text,";
s+="esthetics text, phyto text,miscellaneous text)";
//s="SELECT * FROM ttd_species WHERE speciesId=4";
qWarning( s.toAscii() );
b=q.exec( s );

Executing the query fails with the following information

SQL logic error or missing database
Unable to fetch row
Err number 1.

If the query is remplaced by the commented one, I got no error. If I open my
database file with sqliteman, the query is executed without any problem.
Some ideas ?

TIA

Alain


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[sqlite] Re: query problem

[Alain Bertrand]

D. Richard Hipp a écrit :




I've changed my mind.  I think instead that there is a bug in
SQLite that caused LEFT JOINs to be computed incorrectly if one
of the terms in the ON clause restricts only the left table in
the join.  


Check-in [2725] at http://www.sqlite.org/cvstrac/chngview?cn=2725
contains
a fix for this problem for version 3.x.  The problem has existed in
SQLite
forever (because it originates from a conceptual misunderstanding by the
code author :-)) so version 2.8.16 is still broken.  Because the problem
is obscure, I am not inclined to fix it in the 2.8.x series...

Thanks for your answer. Do you have an approximativ dateframe to see 
this fix incorporated in a release ?



Alain

[sqlite] Re: query problem

[Alain Bertrand]

Puneet Kishor a écrit :


without seeing the data, a good guess would be, "Yes."

What do you mean ? That my query is syntaxically wrong ?


LEFT JOIN selects all the rows with values from the left table and 
either matching values or NULL from the right table.
Yes, I know, not very well because I have only a basic knowledge of sql 
(this query has been written by a friend), but this is what I want.
This may look complicated for just counting the number of rows, but in 
fact this a kind of minimum example to reproduce the problem I have with 
a more complex query.


Regards,
Alain

[sqlite] query problem

[Alain Bertrand]

hi all,

I am porting a program from mysql to sqlite.
The following statement doesn't work correctly with sqlite though it does
with mysql.
SELECT COUNT(*) AS nb FROM ttd_photos LEFT JOIN ttd_trees ON
ttd_photos.kind=1 AND ttd_photos.refId=ttd_trees.treeId LEFT JOIN ttd_pots
ON ttd_photos.kind=2 AND ttd_photos.refId=ttd_pots.potId

In my test case, it reports 0 where it should report 2. This is the LEFT
JOIN part which has a problem ;)

Any idea ?

Thanks,

Alain