Could not insert data into Sqlite database

[Fuel]

try db.lastError()

[mrjj]

@mark_ua_1999
So q.lastError().text() do not give any text?
even exec fails?

You can also try
QString QSqlQuery::lastQuery() const
to see what all that code becomes.
Its most likely something trivial.

Are there any reason you are not using bound parameters to get a cleaner looking code ?

 QSqlQuery query;
    query.prepare("INSERT INTO person (id, forename, surname) "
                  "VALUES (:id, :forename, :surname)");
    query.bindValue(":id", 1001);
    query.bindValue(":forename", "Bart");
    query.bindValue(":surname", "Simpson");
    query.exec();

[mark_ua_1999]

@mrjj I have tried but failed my code

[mrjj]

@mark_ua_1999
Check if prepare returns true

[SGaist]

Hi,

Before anything, check that the database opens successfully and print what happens if it fails. Also please post the configuration you used for your database.

[mrjj]

Hi
as a note
http://sqlitebrowser.org/
is very useful if db is sqllite. To examine database and test queries

[mark_ua_1999]

@mrjj I change my QSqlDatabase object (before I could not open the bd now can) my code but now got another problem "Parameter count mismatch" mayby it
will be more clear for you to see where

[SGaist]

Which version of Qt are you using ?

[mark_ua_1999]

@SGaist Qt 5.3

[SGaist]

Then change to positional placeholders. Support for named placeholder for the sqlite driver has been added to Qt 5.10 IIRC.

[mark_ua_1999]

@SGaist , @mrjj,@Fuel
Thanks all for help now I could insert lines and have another question- about the performence, it takes a lot of time to read the data(it could disturb the user) do you have any ideas about it?(Maybe it depends on tables count in db)

[mrjj]

@mark_ua_1999
How many rows do you have?
And how are you reading it ?
Normally its pretty fast but if you loop all rows and say add as text
to a textbrowser it can be really slow.

So please show what you are doing :)

[mark_ua_1999]

@mrjj CODE - mainwindow Dialog
In dialog I create train route in main I show available train routes responding time is very long (when add new train)
;

[mrjj]

Hi
setCellWidget can be heavy.
But you only show 5 row here.
How many do you have?

Is it the on_actionAdd_train_triggered that takes time?

[mark_ua_1999]

@mrjj When I click ok in Dialog window it takes a lot of time to add new row in mainwindow have no ideas why

[mrjj]

@mark_ua_1999
well you loop a file in on_actionAdd_train_triggered but do nothing with what it reads.
I do not think reading from database is the slow part and setCellWidget x5 should be that heavy unless its
a Pi board or slower pc.

[mark_ua_1999]

@mrjj I will be trying to show visual result adding the new train firstly and only than write to db it must help

[mrjj]

@mark_ua_1999
Sounds like a good plan. IF you only show 5 at a time, its odd it should be slow.

[mark_ua_1999]

@mrjj I am trying to create and insert information in db in mainwindow the db is opened
but the program crashes after if(query.exec("CREATE TABLE "+e.train_name+" "
"(id integer primary key)" )) what could be a matter
void MainWindow::on_actionAdd_train_triggered()
{
Dialog e;
if(e.exec())
{
if(e.duplicate == "")
{
Add(e.Cities);

    QSqlQuery query;
     //таблиця міст через які їхатиме поїзд
    // train_name = s;
     QSqlDatabase db_ = QSqlDatabase::addDatabase("QSQLITE");
    db_.setDatabaseName("C:\\SQLiteDatabaseBrowserPortable\\Data\\cities.db");
     db_.open();
     if(db_.isOpen())
     {
         ui->lineEdit->setText("oPEN " + e.train_name);
     }

     if(query.exec("CREATE TABLE "+e.train_name+" "
                                                 "(id integer primary key)"

                                                 ))       
             ui->lineEdit->setText("Created");
     db_.close();

[mrjj]

@mark_ua_1999
The easiest way to find crash is to use the debugger.
Place a break point and single step the code.
Then you can see what makes it crash.