primary_expression ::= 
   parenthesized_expression |
   constant_expression |
   column_reference |
   variable_reference |
   array_constructor |
   map_constructor |
   case_expression |
   cast_expression |
   extract_expression |
   function_call |
   count_star |
   transform_expression

The following subsections describe each of the primary expressions listed in the above grammar rule, except from count_star, which is the count(*) aggregate function defined in the Using Aggregate Functions section.