Saving to SQLite from text edit (help pwetty pwease)

[Scottish_Jason]

@p3c0 - p3c0 the error returns "true" ??? The application also locks up and / or crashes

if (db4.open())
{
    QSqlQuery query(db4);
    int rowcount1 = ui->physicaltable->rowCount();
    int rowcount2 = ui->logicaltable->rowCount() - 1;
    if (rowcount1 > 0)
    {
    QString dp1 = ui->physicaltable->item(0,0)->text();
    QString cp1 = ui->physicaltable->item(0,1)->text();

    query.prepare("UPDATE sensors SET pin1 = :dp, attached_gpio = :cp WHERE sensor_name = 'FC-28';");
    query.bindValue(":dp", dp1);
    query.bindValue(":cp", cp1 );
    if (query.exec())
         {
        qDebug() << "inserted";
         }
         else
        {
        qDebug() << QSqlQuery::lastError;
        }

    }

}

[p3c0]

@Scottish_Jason No. You didn't use it properly. I posted it like that just for the sake of that link. Try :

query.exec()
...
qDebug() << query.lastError() << query.lastError().text();
//Also some other useful methods
qDebug() << query.lastQuery();
qDebug() << query.executedQuery();

[Scottish_Jason]

@p3c0

QSqlError("5", "Unable to fetch row", "database is locked") "database is locked Unable to fetch row"

I am unsure how to handle databases... so far I have been opening and closing them on each function since I can't call db.whatever if I have not initialized it, or the lack of it being a global variable. Is this my issue?

[p3c0]

@Scottish_Jason Don't do that. Instead open the connection only once. QSqlQuery will always use this default connection.

[Scottish_Jason]

@p3c0

When I take out the secondary QSqlQuery query(db) lines I always end up with query was not declared. How do I initialize the database per function? it has always confused me until now

[p3c0]

@Scottish_Jason Check this example specifically the createConnection method. Modify it as per your need.

[Scottish_Jason]

@p3c0 Thanks, but what if I want to use the same database throughout many functions?
how do I pass the db variable to open?

[p3c0]

@Scottish_Jason That is what is default connection. It is available across all functions or classes. Just use QSqlQuery directly or you can also try

QSqlQuery query(QSqlDatabase::database())

in this case it will return the default one.

[Scottish_Jason]

@p3c0

well guys, thanks for the help but I think I really need to hang up the hat on this one... no matter how I try to initialize the database on a second function ( or lack of initilization) I either get database not open or duplicate database open that causes instability and crashes.

I have been up all night trying to get it working so maybe I'm just tired but I'm starting to think this might be a bit over my head. Thanks for the help guys

[p3c0]

@Scottish_Jason I would suggest you to start from some simple examples keeping the earlier example code in mind ofcourse after some sleep. It works :)

[Scottish_Jason]

@p3c0

The strange thing is I am only implementing this block once in my loadsensors() function

QString dbname = "sensors";
QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
db.setDatabaseName("sensors.sqlite");
QSqlQuery query(QSqlDatabase::database());

and then just QSqlQuery query; in the following functions but it still insists that the database is locked.
( I need query defined so I can do the prepare's etc on each function )

I probably sound awfully silly right now but I'm kinda struggling coming from a php mainly background to this. Any hints down the correct path would be appreciated

[clochydd]

@Scottish_Jason
Hi, what happens, if you declare your query that way:

QSqlQuery query;
...
query = QSqlQuery(db);

[clochydd]

@Scottish_Jason

You are using DB Browser for SQLite parallel - is there a chance that it locks your database?

[Scottish_Jason]

@clochydd said:

@Scottish_Jason

You are using DB Browser for SQLite parallel - is there a chance that it locks your database?

YAYYY thanks so much.
the browser itself was the culprit. Values are being updated now.

Thank you all +reps

one last question if I may:

instead of dropping the data into the 'FC-28' column I would like it to drop it under the name of whatever is selected on another table, any help in that direction?

query.prepare("UPDATE sensors SET pin1 = :dp, attached_gpio = :cp WHERE sensor_name = "selected item on sensor_table");
query.bindValue(":dp", dp1);
query.bindValue(":cp", cp1 );

[p3c0]

@Scottish_Jason Do it in the same way which you did for the other placeholders viz. for eg. :dp and :cp in your example.

[clochydd]

@Scottish_Jason
Hi Jason, may look like:

QString mySearch;
...
mySearch = "FC-28";
query.prepare("UPDATE sensors SET pin1 = :dp, attached_gpio = :cp WHERE sensor_name = :search;");
query.bindValue(":dp", dp1);
query.bindValue(":cp", cp1 );
query.bindValue(":search", mySearch );