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    <p><strong>Note:</strong> This answer is similar to the other two, but I'll post it anyway because it defines the trigger differently in a way that may be useful. <em>Please note that I've up-voted the other two answers as they'll do the job nicely.</em></p> <p>First, if you're only interested in changes to the <code>DEPARTMENT_ID</code> column, you can specify that in your trigger definition:</p> <pre><code>CREATE OR REPLACE TRIGGER employee_dept_trigger BEFORE INSERT OR UPDATE OF department_id ON employee FOR EACH ROW .... </code></pre> <p>A trigger can use the "automatic" logical values <code>INSERTING</code> and <code>UPDATING</code> to determine if an insert or an update called it. You can use the <code>INSERTING</code> value to indicate that this is a new employee:</p> <pre><code>IF INSERTING THEN -- set old department name = 'N/A' ELSE -- set old department name = whatever END IF; </code></pre> <p>Your question doesn't describe where the department <em>name</em> comes from, so this example descends into pseudocode when it comes to the department names:</p> <pre><code>CREATE OR REPLACE TRIGGER employee_dept_trigger BEFORE INSERT OR UPDATE OF department_id ON employee FOR EACH ROW BEGIN IF INSERTING THEN -- New employee INSERT INTO employee_dept_history VALUES ( :NEW.employee_id, :NEW.employee_name, 'N/A', (SELECT department_name from ...), &lt;-- based on :NEW.department_id SYSDATE); ELSE -- Existing employee INSERT INTO employee_dept_history VALUES ( :NEW.employee_id, :NEW.employee_name, (SELECT department_name from ...), &lt;-- based on :OLD.department_id (SELECT department_name from ...), &lt;-- based on :NEW.department_id SYSDATE); END IF; END employee_dept_trigger; </code></pre>
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