code: package it.unibz.inf.ontop.model.term.functionsymbol.db.impl;
  
  import com.google.common.collect.ImmutableList;
  import it.unibz.inf.ontop.iq.node.VariableNullability;
  import it.unibz.inf.ontop.model.term.DBConstant;
  import it.unibz.inf.ontop.model.term.ImmutableFunctionalTerm;
  import it.unibz.inf.ontop.model.term.ImmutableTerm;
  import it.unibz.inf.ontop.model.term.TermFactory;
  import it.unibz.inf.ontop.model.term.functionsymbol.FunctionSymbol;
  import it.unibz.inf.ontop.model.type.DBTermType;
  
  import java.util.Optional;
  import java.util.function.Function;
  
  public class AbstractTimestampISODenormFunctionSymbol extends AbstractDBTypeConversionFunctionSymbolImpl {
  
      private final static String CAST_TEMPLATE = "CAST(%s AS %s)";
      private final DBTermType dbStringType;
  
      protected AbstractTimestampISODenormFunctionSymbol(DBTermType timestampType, DBTermType dbStringType) {
          super("isoTimestampDenorm", dbStringType, timestampType);
          this.dbStringType = dbStringType;
      }
  
      @Override
      public Optional<DBTermType> getInputType() {
          return Optional.of(dbStringType);
      }
  
      @Override
      public boolean isTemporary() {
          return false;
      }
  
      @Override
      public boolean isSimple() {
          return false;
      }
  
      @Override
      public boolean isAlwaysInjectiveInTheAbsenceOfNonInjectiveFunctionalTerms() {
          return true;
      }
  
      @Override
      public boolean canBePostProcessed(ImmutableList<? extends ImmutableTerm> arguments) {
          return false;
      }
  
      protected ImmutableTerm buildTermFromFunctionalTerm(ImmutableFunctionalTerm subTerm, TermFactory termFactory,
                                                          VariableNullability variableNullability) {
          FunctionSymbol subTermFunctionSymbol = subTerm.getFunctionSymbol();
          // TODO: avoid relying on a concrete class
          if (subTermFunctionSymbol instanceof AbstractTimestampISONormFunctionSymbol) {
              DBTermType targetType = getTargetType();
              ImmutableTerm subSubTerm = subTerm.getTerm(0);
  
              return ((AbstractTimestampISONormFunctionSymbol) subTermFunctionSymbol).getInputType()
                      // There might be several DB datetime types
                      .filter(t -> !t.equals(targetType))
                      .map(t -> termFactory.getDBCastFunctionalTerm(t, targetType, subSubTerm).simplify(variableNullability))
                      .orElse(subSubTerm);
          }
          return termFactory.getImmutableFunctionalTerm(this, ImmutableList.of(subTerm));
      }
  
      @Override
      protected ImmutableTerm convertDBConstant(DBConstant constant, TermFactory termFactory) {
          String newString = constant.getValue()
                  .replace("T", " ")
                  //.replaceFirst("([+-]\\d\\d:\\d\\d)", " $0")
                  //.replace("Z", " +00:00");
                  .replace("Z", "+00:00");
  
          return termFactory.getDBConstant(newString, getTargetType());
      }
  
      @Override
      public String getNativeDBString(ImmutableList<? extends ImmutableTerm> terms,
                                      Function<ImmutableTerm, String> termConverter, TermFactory termFactory) {
          ImmutableFunctionalTerm replaceTTerm = termFactory.getDBReplace(terms.get(0),
                  termFactory.getDBStringConstant("T"),
                  termFactory.getDBStringConstant(" "));
  
          ImmutableFunctionalTerm newTerm = termFactory.getDBReplace(replaceTTerm,
                  termFactory.getDBStringConstant("Z"),
                  termFactory.getDBStringConstant("+00:00"));
  
          return String.format(CAST_TEMPLATE, termConverter.apply(newTerm), getTargetType().getCastName());
      }
  }
  