**Use case**

Workload generation with continuous queries.

**Describe the solution you'd like**

Similar to now() but non-constant.

void registerFunctionAddMicroseconds(FunctionFactory &);
void registerFunctionAddMilliseconds(FunctionFactory &);
void registerFunctionAddSeconds(FunctionFactory &);
void registerFunctionAddMinutes(FunctionFactory &);
void registerFunctionAddHours(FunctionFactory &);
void registerFunctionAddDays(FunctionFactory &);
void registerFunctionAddWeeks(FunctionFactory &);
void registerFunctionAddMonths(FunctionFactory &);
void registerFunctionAddQuarters(FunctionFactory &);
void registerFunctionAddYears(FunctionFactory &);
void registerFunctionSubtractNanoseconds(FunctionFactory &);
void registerFunctionSubtractMicroseconds(FunctionFactory &);
void registerFunctionSubtractMilliseconds(FunctionFactory &);
void registerFunctionSubtractSeconds(FunctionFactory &);
void registerFunctionSubtractMinutes(FunctionFactory &);
void registerFunctionSubtractHours(FunctionFactory &);
void registerFunctionSubtractDays(FunctionFactory &);
void registerFunctionSubtractWeeks(FunctionFactory &);
void registerFunctionSubtractMonths(FunctionFactory &);
void registerFunctionSubtractQuarters(FunctionFactory &);
void registerFunctionSubtractYears(FunctionFactory &);
void registerFunctionDateDiff(FunctionFactory &);
void registerFunctionDateName(FunctionFactory &);
void registerFunctionMonthName(FunctionFactory &);
void registerFunctionToTimeZone(FunctionFactory &);
void registerFunctionFormatDateTime(FunctionFactory &);
void registerFunctionFromModifiedJulianDay(FunctionFactory &);
void registerFunctionDateTrunc(FunctionFactory &);
void registerFunctiontimezoneOffset(FunctionFactory &);
void registerFunctionsDateTime(FunctionFactory & factory)