Question

I’m trying to delete with qt with this code:

int jobId = 655;
query.prepare("DELETE FROM jobs WHERE jobId = '" + QString::number(jobId) + "'");
QString error = query.lastError().text();
if (query.exec())
    qDebug() << "DELETE ok";
else
    qDebug() << error;

if jobId exist all fine but if not exit too show “DELETE ok”.

How can I check this situation?.

Thanks you very much

Answer 1

A DELETE query doesn’t generate error if it has nothing to delete.

You might be able to find if something was deleted with QSqlQuery::numRowsAffected.

But if you want to know if the id exists before deleting it, you have to do a separate SELECT request for that id.

PS: you should use addBindValue or bindValue to insert values in the query string:

query.prepare("DELETE FROM jobs WHERE jobId = ?");
query.addBindValue(jobId);