Insert data from variables to Database

Lazar1

Good morning.

I am working on a project and while i am able to send numbers to my MYSQL database with this code:

QSqlQuery query;
query.prepare("INSERT INTO vathmoi (V_1) "
"VALUES (10)");
query.exec(); // this runs it

i can not send data using that code

QString b;
b=10;
QSqlQuery query;
query.prepare("INSERT INTO vathmoi (V_1) "
"VALUES (b)");
query.exec(); // this runs it

So i dont know how to handle that isue cause in the project i am developing all that wich are going to be stored in the db are in variables.

Thank you in advance.

micland

You can reference variables in your quere using bindValue(...):

query.prepare("INSERT INTO vathmoi (V_1) VALUES (:myValue)");
query.bindValue(":myValue", b);
query.exec();
// ....

See also these examples: http://doc.qt.io/qt-5/sql-sqlstatements.html#inserting-updating-and-deleting-records

mrjj

Hi and good morning :)
Your syntax still looks wrong. ( use syntax as @micland shows)
and please also use
if(!query.exec()) {
qDebug() << "SQL Statement Error" << query.lastError();
}
as @the_
mentions in
https://forum.qt.io/topic/68149/connect-mysql-database-to-qt-app/4

micland

@Lazar1
Aye! right - as @mrjj said never drop the error handling because you can't be sure that your backend is (still) up and running and works as expected... a useful error handling may prevent a lot of debugging.

mrjj

Just a note:
QString b;
b=10;
qDebug() << b;

Does NOT give u "10" but ascii 10
b=65
would give u "A"

QString b;
b=QString::number(10);

Give you "10".

Lazar1

Thank you all for your quick and correct ansewrs everything works fine now and i have learned a lot about debuging through your comments and i ll be sure to use it well in my programms. I will now close the topic again thanks for everything