The SQLite exception "no such table: <table> Unable to execute statement" with QSqlDatabase

Maarouf Med Mahdi

I copied the same database (exported) and put it in the directory of my project. and I checked with notepade that all the tables are created, in the end I gave it to QT by the way of this last database

Maarouf Med Mahdi

@Stoyan that query
select * from sqlite_master where tbl_name = 'serveurs';
works in the both

Stoyan

@Maarouf-Med-Mahdi
It always works. The question is how many rows returns in each case.

Maarouf Med Mahdi

@Stoyan -1
QString text_req = "select * from sqlite_master where tbl_name='serveurs'";
if(requette.exec(text_req))
qDebug()<<"requette valide"<<requette.size();
else
qDebug()<<"invalide requette"<<" --> "<<requette.lastError().text();
connected
requette valide -1

Stoyan

@Maarouf-Med-Mahdi
Unfortunately, SQLite doesn't support QSqlQuery::size() function.
Instead you can use this:

if(requette.exec(text_req))
{
    requette.last();
    qDebug() << requette.at() + 1;
}

Maarouf Med Mahdi

@Stoyan that give me -1 again

Stoyan

@Maarouf-Med-Mahdi
You should just change directory separator in your code from "\" to "/".
I make some tests with this code:

    QSqlDatabase mydb = QSqlDatabase::addDatabase("QSQLITE");
    mydb.setDatabaseName("C:\Projects\Test\BD.db");
    if(!mydb.open())
    {
        qDebug() << mydb.lastError().text();
    }
    qDebug() << "Tables: " << mydb.tables();
    quint16 cnt = 0;
     QSqlQuery q;
     QString text_req = "select * from sqlite_master where tbl_name='serveurs'";
     if(q.exec(text_req))
     {
         while(q.next())
         {
             cnt++;
         }
         qDebug() << "Records count: " << cnt;
     }
     else
         qDebug()<<"Invalide query"<<" --> " << q.lastError().text();

On compile it give warnings:

warning: unknown escape sequence: '\P'
warning: unknown escape sequence: '\T'
warning: unknown escape sequence: '\B'

The result was this (just like yours):

Tables:  ()
Records count:  0

When I change this row:

    mydb.setDatabaseName("C:\Projects\Test\BD.db");

with this:

    mydb.setDatabaseName("C:/Projects/Test/BD.db");

there are no warnings, everything works and the result is:

Tables:  ("serveurs", "historiques")
Records count:  2

Maarouf Med Mahdi

Just I want to give my experience result or a advice about this and to don't repeate to other members.
Sometimes, Qt does not accept an absolute path of the database file if it is not in the
same output program file (Debug or Release).
If Qt can not recover your database file, it will create a new empty database in the same output program folder. this can make the not such table sql error .
I want to thank all the members they help me for finding my proposed solution.

SGaist

Hi,

That's unrelated to Qt. It's how SQLite behaves. If there's no file matching the parameter you give it, it will create it. What you can do is check the file existence with QFile.

Maarouf Med Mahdi

Hi @SGaist
Thanks for that SQLite information . I checked that .
all what i did to find that solution, i have moved the DataBase file to the output folder .