Changes between Initial Version and Version 1 of Trigger6

Timestamp:

08/21/26 08:06:10 (27 hours ago)

Author:

235018

Comment:

--

Trigger6

@@ +1 @@
+= Automatic setting of the last modified date for orders
+
+=== Description
+This trigger automatically updates the last_modified_date attribute whenever an existing order is changed.
+
+The application does not need to manually provide the modification timestamp. The database automatically records the exact time when the order was modified.
+
+==== Tables involved
+- Order
+
+==== Type of trigger
+- BEFORE UPDATE
+
+Activated on the `Order` table.
+
+==== SQL Code
+{{{#!sql
+CREATE OR REPLACE FUNCTION update_order_modified_date() 
+RETURNS TRIGGER 
+LANGUAGE plpgsql 
+AS $$ 
+BEGIN 
+    NEW.last_modified_date := CURRENT_TIMESTAMP; 
+    RETURN NEW;
+END; 
+$$; 
+
+CREATE TRIGGER trg_update_order_modified_date 
+BEFORE UPDATE 
+ON "order" 
+FOR EACH ROW 
+EXECUTE FUNCTION update_order_modified_date();
+
+}}}
+
+=== Logic explanation
+
+Whenever an order is updated, the trigger:
+
+**1.** Detects the update operation.
+**2.** Gets the current timestamp using CURRENT_TIMESTAMP.
+**3.** Stores the timestamp in NEW.last_modified_date.
+**4.** Allows the updated order to be saved.
+
+=== Reason for trigger
+
+This trigger is useful because:
+
+- t automatically tracks order modifications.
+- It prevents incorrect or missing modification timestamps.
+- It removes the responsibility from the application layer.
+- It provides a reliable history of when an order was last changed.