buggy behavior of : bool QAbstractItemModel::removeRow(int row, const QModelIndex &parent = QModelIndex())

when i ovveride the data function in my QSQLtableModel in two way the executtion of the removeRow return true but in one way affected in database and in other way not working properly(againt return true but not change in database).

1 - 

switch(role)

{ case Qt::DisplayRole: return QSqlTableModel::data(idx,role); default:break; }

 

2 - 

switch(role)

{ case Qt::DisplayRole: return QSqlTableModel::data(idx,role); default: return QVariant();  }