Detect if SQLite UPDATE statement does not actually update anything

[Kofr]

I use statement like this

QString queryContent = "UPDATE \'" + parentName + "\' SET " + column + " = :value WHERE row = " + QString::number(t_row);

Row is the Primary Index.
When I execute query with for example t_row = 60 and such table contains 55 row, the UPDATE statement is executed successfully with no errors, but does not updait anything.
How to make SQL query fail in such case, so I can detect the incorrect data?
ps. UPDATE OR FAIL does not help in case with WHERE filtering.

[Paul Colby]

Hi @Kofr,

... the UPDATE statement is executed successfully with no errors, but does not updait anything.
How to make SQL query fail in such case, so I can detect the incorrect data?

You can use QSqlQuery::numRowsAffected(), eg:

if (query.numRowsAffected() < 1) {
    // no rows were updated - handle this however you like.
}

Cheers.

[Kofr]

@Paul-Colby thx for the answer. QSqlQuery::numRowsAffected() does not work with SQLite

[SGaist]

Hi,

Strange, this is implemented in the plugin. Which version of Qt are you using ?

[Kofr]

@SGaist I use Qt 5.7.0
query.numRowsAffected() returns -1
and driver.hasFeature(QSqlDriver::QuerySize) returns false

[SGaist]

QuerySize is not the same thing as numRowsAffected.

QuerySize is for whether the driver is able to give the number of rows returned by a query.

[Kofr]

@SGaist there is no other argument in hasFeature(QSqlDriver::???) for checking for numRowsAffected()
and query.numRowsAffected() returns -1 all the time even if UPDATE's succesful. So far in my case.

[SGaist]

Can you show how you setup and run your query ?