Is it okay to have type checking code when working with databases?

I'm trying to insert some code into a database. But, i have encountered a problem while working with models that are subclasses of each other. I have a list that holds all these subclases.

List<Metric> metrics = experiment.getMetrics();

for(Metric m : metrics) {
    int id = m.getId();
    // type checking code

}

Metric has sublcases of Rating and Quantity. Each of these in turn have there own uniquely defined tables. I am conflicted over the idea of using type checking. But I don't see any immediate solution. One alternative, which doesn't seem any better, would be to create a new column in the Metric table called metric_type. But this would lead to something quite similar to type checking. Any suggestions?