Enforce uniqueness on short_code + expiry_date + user_id via DB trigger

dbConfig/index.js

@@ -72,6 +72,15 @@ const initDB = async () => {
                         SELECT 1 FROM urls
                         WHERE user_id = NEW.user_id AND customized_shortner_slug = NEW.customized_shortner_slug
                       );
+
+                     -- Case 3: Prevent reinserting same short_code + expiry_date + user_id + slug (if slug is not null)
+                      SELECT RAISE(ABORT, 'Duplicate URL record not allowed')
+                      WHERE EXISTS (
+                        SELECT 1 FROM urls
+                        WHERE short_code = NEW.short_code
+                          AND expiry_date = NEW.expiry_date
+                          AND user_id = NEW.user_id
+                      );  
                   END;
                 `,
                 function (err) {