Doesn't update or delete if primary key is string.

[nasanjargal-b]

I found and fix the error of doesn't update or delete if primary key is string.

I solved this issue as below:

sqlgeneratorbase.cpp

*QString SqlGeneratorBase::updateRecord(Table t, QString tableName)**

    sql = QString("UPDATE %1 SET %2 WHERE %3=%4")
            .arg(tableName)
            .arg(values.join(", "))
            .arg(key)
            .arg(val.type() == QVariant::String ? "\'" + val.toString() + "\'" : val.toString());

*QString SqlGeneratorBase::deleteRecord(Table t, QString tableName)**

    QString sql = QString("DELETE FROM %1 WHERE %2='%3'")
            .arg(tableName)
            .arg(t->primaryKey())
            .arg(val.type() == QVariant::String ? "\'" + val.toString() + "\'" : val.toString());