[Interest] SQLite: mystic bug: No query Unable to fetch row error

[Alexander Dyagilev]

Hello,

Each instance of our app is supposed to have an unique id (UUID).

At every start, it check if it has assigned one, and if not - generates 
it and saves it to the SQLite database.

We've found, that 4% of ours users has empty UUIDs.

We've added some diagnostic reporting info and found, that this is 
caused by SQLite database not being able to write generated UUID to it.

QSqlQuery::exec returns false and its last error returns this error "No 
query Unable to fetch row error".

How can this be? I could not find any problems working with the database 
in our code.

We do it so:

1. Make sure the table exists:

"CREATE TABLE IF NOT EXISTS miscData (Name TEXT, Value BLOB, PRIMARY KEY 
(Name))"

2. Write value to the table:

QSqlQuery query(m_db);
query.prepare("REPLACE INTO miscData (Name, Value) VALUES (:Name, :Value)");
query.bindValue(":Name", "UUID");
query.bindValue(":Value", UuidByteArray);

if (!query.exec())
{
      // here we're getting this error....
}

What are the possible reasons of this error?