title: ORA-02287: sequence number not allowed here
body: <p>I am trying to select values from two tables and insert them into one table and calculate the number of placements in total per year. I keep getting an error saying sequence not allowed here</p>
  
  <pre><code>DROP table placement_cal CASCADE CONSTRAINTS;
  
  CREATE TABLE placement_cal(
      cal_id  INTEGER NOT NULL,
      year    INTEGER,
      no_of_placements INTEGER,
      CONSTRAINT  pk_cal_dim PRIMARY KEY (cal_id)
  );
  
  
  INSERT INTO placement_cal (
  SELECT cal_id.nextval  , EXTRACT(YEAR FROM start_date) , count(placement_id)
  FROM placement
  group by year);
  
  INSERT INTO placement_cal (
  SELECT cal_id.nextval  , EXTRACT(YEAR FROM start_date) , count(placement_id)
  FROM placement_two
  group by year);
  </code></pre>