Oracle 18c

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create table cs_transassignment_26weeks (id int);
declare v_datacount_backuptable int;
begin
  EXECUTE IMMEDIATE 'SELECT /*+ parallel (8) */ COUNT(1) INTO '
      ||v_datacount_backuptable||
      ' FROM cs_transassignment_26weeks';
end;
/
ORA-00936: missing expression
ORA-06512: at line 3

declare v_datacount_backuptable int;
begin
  SELECT /*+ parallel (8) */ COUNT(1) INTO v_datacount_backuptable FROM cs_transassignment_26weeks;
  dbms_output.put_line(v_datacount_backuptable);
end;
/
1 rows affected

dbms_output:
0

declare 
    v_datacount_backuptable int;
    v_query varchar(500);
begin
  v_query := 'SELECT /*+ parallel (8) */ COUNT(1) FROM cs_transassignment_26weeks';
  EXECUTE IMMEDIATE v_query INTO v_datacount_backuptable;
  dbms_output.put_line(v_datacount_backuptable);
end;
/
1 rows affected

dbms_output:
0