First i try the code below on sql developer and works fine:

FECHA IS A ORACLE DATE TYPE

@
SELECT idgasto, concepto, monto, TO_CHAR(fecha, 'dd-MM-yyyy'), observaciones
FROM GASTOS WHERE concepto='KEVIN'
AND TO_DATE(fecha,'dd-MM-yyyy') >= TO_DATE('01-09-1988' ,'dd-MM-yyyy')
AND TO_DATE(fecha,'dd-MM-yyyy') < TO_DATE('1-10-1988','dd-MM-yyyy')
ORDER BY (fecha)
@

i get 1 row (the onlyone i had on this table):

@
IDGASTO CONCEPTO MONTO TO_CHAR(FECHA,'DD-MM-YYYY') OBSERVACIONES

3 KEVIN 10000 12-09-1988 aaaaaaaaaaaaa
@

so when i try the code below in my model i get 0 rows

@
void BuscarGasto::on_pushButtonBuscar_clicked()
{
model->setQuery("SELECT idgasto, concepto, monto, TO_CHAR(fecha, 'dd-MM-yyyy'), observaciones "
" FROM GASTOS WHERE concepto='KEVIN' "
" AND TO_DATE(fecha,'dd-MM-yyyy') >= TO_DATE('01-09-1988' ,'dd-MM-yyyy') "
" AND TO_DATE(fecha,'dd-MM-yyyy') < TO_DATE('1-10-1988','dd-MM-yyyy') "
" ORDER BY (fecha) ", db);
qDebug()<<model->query().lastError().text();
ui->tableView->setModel(model);
}
@

but when i try the code below i get the same row that i got with sqldeveloper so....:

@
void BuscarGasto::on_pushButtonBuscar_clicked()
{
model->setQuery("SELECT idgasto, concepto, monto, TO_CHAR(fecha, 'dd-MM-yyyy'), observaciones "
" FROM GASTOS WHERE concepto='KEVIN' "
" ORDER BY (fecha) ", db);
qDebug()<<model->query().lastError().text();
ui->tableView->setModel(model);
}
@

so the problem is somewhere in the lines below wich are exactly the same as i tried on sqldeveloper....

@
" AND TO_DATE(fecha,'dd-MM-yyyy') >= TO_DATE('01-09-1988' ,'dd-MM-yyyy') "
" AND TO_DATE(fecha,'dd-MM-yyyy') < TO_DATE('1-10-1988','dd-MM-yyyy') "
@

the ouput of qDebug() is " ";

other information: i use oracle express edition 11g

so no clue where is the problem i tried everything that came to my head :(

i dont post more information bcz the post is already to long and i dont think more infomation gona be usefull