title: Self Referencing FK - The UPDATE statement conflicted with the FOREIGN KEY constraint
body: <p>I have a test table <strong>employee</strong> which have self referencing FK <strong>manager_id</strong>:</p>
  <pre><code> CREATE TABLE employee (
     employee_id int IDENTITY PRIMARY KEY, 
     employee_name varchar(30), 
     salary varchar(30), 
     manager_id int
  );
  
   ALTER TABLE employee
      ADD CONSTRAINT sr_fk_emp_man 
      FOREIGN KEY (manager_id)
      REFERENCES employee(employee_id)
  ;
  
   INSERT INTO employee (employee_name, salary) VALUES 
     ('ISACC NEWTON', 732611),
     ('ROMEO', 329827);
  
   UPDATE employee SET manager_id = 21 WHERE employee_name = 'ROMEO';
  </code></pre>
  <p>Error occurs when I set for PK <strong>employee_id</strong> int IDENTITIY:</p>
  <pre><code>The UPDATE statement conflicted with the FOREIGN KEY SAME TABLE constraint &quot;sr_fk_emp_man&quot;.
  The conflict occurred in database &quot;master&quot;, table &quot;dbo.employee&quot;, column 'employee_id'.
  </code></pre>
  <p>I need to have for PK numeric column that is automatically populated.</p>
  <p>I tried to solve a problem with adding sequence instead of IDENTITIY, adding Referential integrity for FK (ON DELETE CASCADE ON UPDATE CASCADE) and set for FK NULL value but nothing changes. I could use <strong>WITH NOCHECK</strong> Constraint but I read that is not the safest option. I am using MS SQL Server.</p>