How do I find the largest primary key in a model?

jdent

I need to insert a record doing

model->insertRecord(-1, sqlRecord);

but to insert, I need to specify a new and large enough primary key. How can I obtain the largest primary key in a model??
Also, after inserting how can I make that row the current in a tableView?

Regards,
Juan

jsulm

@jdent said in How do I find the largest primary key in a model?:

How do I get the value?

By reading documentation: https://doc.qt.io/qt-6/qsqlquery.html#value
There is also an example:

QSqlQuery query("SELECT country FROM artist");
while (query.next()) {
    QString country = query.value(0).toString();
    doSomething(country);
}

jsulm

@jdent said in How do I find the largest primary key in a model?:

I need to specify a new and large enough primary key.

Why? Primary keys are usually auto-increment and you do not specify them explicitly.

jdent

@jsulm Yet for my case I need to know the largest primary key... Please

jdent

@jdent Also, is there no updateRecord()? if insertRecord is the way how do I find the row number of the model?

jsulm

@jdent Well, then you will have to query it using max(): https://www.w3schools.com/sql/sql_min_max.asp
But keep in mind that between querying the max primary key and inserting the record another transaction could increase the primary key. You should do the querying and inserting in one transaction.

jdent

@jsulm how do I get the value result of the query? I used this:

    QSqlQuery query;

    bool ok = query.exec("select max(id) from location");

How do I get the value?

jsulm

@jdent said in How do I find the largest primary key in a model?:

How do I get the value?

By reading documentation: https://doc.qt.io/qt-6/qsqlquery.html#value
There is also an example:

QSqlQuery query("SELECT country FROM artist");
while (query.next()) {
    QString country = query.value(0).toString();
    doSomething(country);
}

jdent

@jsulm if insertRecord is the way to update a row how do I find the row number of the model? For instance, I just inserted a new record, what is the row number so I can call insertRecord to update the new record?