Could not insert data into Sqlite database

[mark_ua_1999]

Hi I am trying to insert data into db in Qt but failed
it is my code hope your advices help to resolve the problem

[Fuel]

you are calling db.close() and then you execute your query. try to close the database after your queries.

[mark_ua_1999]

@Fuel no I open and execute the query and than close like in my code from link) mayby you know another possible matters to resolve it

[Fuel]

ok i see. i made a mistake. but why you create the necessary table after the insert queries?

[mark_ua_1999]

@Fuel I paste it to show the structure of the table

[mrjj]

Hi
query.exec() returns true/false
and you can use
http://doc.qt.io/qt-5/qsqlquery.html#lastError
to see why it went wrong.

[Fuel]

INSERT INTO " +dataB +"(depart_city,arrival_city,firstname,lastname,bot,vagon,place,privilages,distance,ticket_price)"

Maybe try to add a White Space before (depart_city

because actually your query looks like this.

INSERT INTO _people(depart_city,arrival_city,firstname,lastname,bot,vagon,place,privilages,distance,ticket_price)"

[mark_ua_1999]

@mrjj I have tried the following code
if(!q.exec("INSERT INTO " +dataB +"
(depart_city,arrival_city,firstname,lastname,bot,vagon,place,privilages,distance,ticket_price)"
+"values('"+T.passangers[i].left_city+"','"+T.passangers[i].arrival_city+"','"+T.passangers[i].name+"','"
+T.passangers[i].surname+"','"+bot+"','"+T.passangers[i].wagon+"','"+T.passangers[i].place+"','"+privilages+"','"+T.passangers[i].way_distance+"','"+T.passangers[i].ticket_cost+"')"))
{
ui->textBrowser_2->append(q.lastError().text()+" "+QString::number(q.lastError().number()));
}
but the output is only -1 without any description

[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 :)