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 DefaultSQLIsStringEmptyFunctionSymbol extends AbstractDBIsStringEmptyFunctionSymbol {
  
      private static final String TEMPLATE = "(%s = 0)";
  
  
      protected DefaultSQLIsStringEmptyFunctionSymbol(DBTermType dbBooleanType, DBTermType abstractRootDBType) {
          super(dbBooleanType, abstractRootDBType);
      }
  
      @Override
      public String getNativeDBString(ImmutableList<? extends ImmutableTerm> terms,
                                      Function<ImmutableTerm, String> termConverter, TermFactory termFactory) {
          return String.format(TEMPLATE, termConverter.apply(termFactory.getDBCharLength(terms.get(0))));
      }
  }
  