code: package it.unibz.inf.ontop.model.term.functionsymbol.db.impl;
  
  import com.google.common.collect.ImmutableList;
  import it.unibz.inf.ontop.model.term.ImmutableTerm;
  import it.unibz.inf.ontop.model.term.TermFactory;
  import it.unibz.inf.ontop.model.type.DBTermType;
  
  import java.util.function.Function;
  
  public class DefaultSQLDBIsNullOrNotFunctionSymbol extends AbstractDBIsNullOrNotFunctionSymbol {
  
      private final String template;
  
      protected DefaultSQLDBIsNullOrNotFunctionSymbol(boolean isNull, DBTermType dbBooleanTermType, DBTermType rootDBTermType) {
          super(isNull, dbBooleanTermType, rootDBTermType);
          this.template = isNull
                  ?  "%s IS NULL"
                  :  "%s IS NOT NULL";
      }
  
      @Override
      public String getNativeDBString(ImmutableList<? extends ImmutableTerm> terms,
                                      Function<ImmutableTerm, String> termConverter, TermFactory termFactory) {
          return String.format(template, termConverter.apply(terms.get(0)));
      }
  }
  