================================================================================
empty
================================================================================
DO $$ BEGIN END $$;
--------------------------------------------------------------------------------

(source_file
  (do_block
    (block
      (dollar_quote)
      (body)
      (dollar_quote))))

================================================================================
empty(1)
================================================================================
DO $$ DECLARE BEGIN END $$;
--------------------------------------------------------------------------------

(source_file
  (do_block
    (block
      (dollar_quote)
      (declarations)
      (body)
      (dollar_quote))))

================================================================================
many declare(s)
================================================================================
DO $$
DECLARE one text;
DECLARE
    name foo%TYPE;
    age bar%ROWTYPE;
BEGIN END
$$;
--------------------------------------------------------------------------------

(source_file
  (do_block
    (block
      (dollar_quote)
      (declarations
        (var_definition
          (var_declaration
            (identifier)
            (identifier))))
      (declarations
        (var_definition
          (var_declaration
            (identifier)
            (identifier)))
        (var_definition
          (var_declaration
            (identifier)
            (identifier))))
      (body)
      (dollar_quote))))

================================================================================
declare variables
================================================================================
DO $$
DECLARE
    name text;
    age bigint;
BEGIN END
$$;
--------------------------------------------------------------------------------

(source_file
  (do_block
    (block
      (dollar_quote)
      (declarations
        (var_definition
          (var_declaration
            (identifier)
            (identifier)))
        (var_definition
          (var_declaration
            (identifier)
            (identifier))))
      (body)
      (dollar_quote))))

================================================================================
declare with assignment
================================================================================
DO $$
DECLARE
    name text := 'hello';
    age bigint:= (SELECT foo() + 1);
BEGIN END
$$;
--------------------------------------------------------------------------------

(source_file
  (do_block
    (block
      (dollar_quote)
      (declarations
        (var_definition
          (var_declaration
            (identifier)
            (identifier))
          (string))
        (var_definition
          (var_declaration
            (identifier)
            (identifier))
          (select_statement
            (select_item
              (op_expression
                (function_call
                  (identifier))
                (number))))))
      (body)
      (dollar_quote))))

================================================================================
perform
================================================================================
DO $$
BEGIN
    PERFORM foo();
END
$$;
--------------------------------------------------------------------------------

(source_file
  (do_block
    (block
      (dollar_quote)
      (body
        (perform_statement
          (select_item
            (function_call
              (identifier)))))
      (dollar_quote))))

================================================================================
many statements
================================================================================
DO $$
BEGIN
    SELECT 1;
    foo.bar = lower(foo.baz);
    foo.bar := lower(foo.baz);
    RETURN 2;
END
$$;
--------------------------------------------------------------------------------

(source_file
  (do_block
    (block
      (dollar_quote)
      (body
        (select_statement
          (select_item
            (number)))
        (assign_statement
          (identifier)
          (function_call
            (identifier)
            (identifier)))
        (assign_statement
          (identifier)
          (function_call
            (identifier)
            (identifier)))
        (return_statement
          (number)))
      (dollar_quote))))

================================================================================
function call with select
================================================================================
DO $$ BEGIN perform exists(select 1); END $$;
--------------------------------------------------------------------------------

(source_file
  (do_block
    (block
      (dollar_quote)
      (body
        (perform_statement
          (select_item
            (function_call
              (identifier)
              (select_statement
                (select_item
                  (number)))))))
      (dollar_quote))))