value_exp

value_exp 
      ::= 
      num_value_exp 
      | string_value_exp 
      | datetime_value_exp 
      | interval_value_exp 

This rule is called by

-> case_abbreviation
-> case_operand
-> cast_operand
-> derived_column
-> general_set_fct
-> in_value_list
-> result_exp
-> row_value_constructor_elem
-> update_source
-> value_exp_primary
-> when_operand