docs: add sample code when DBDebug is true

Author: kenjis

user_guide_src/source/database/transactions.rst

@@ -32,25 +32,27 @@ contrast, we've implemented a smart transaction system that does all
 this for you automatically (you can also manage your transactions
 manually if you choose to, but there's really no benefit).
 
+.. note:: Since v4.3.0, ``DBDebug`` is true by default in all environments.
+    When ``DBDebug`` is true, if a query error occurs, all the queries
+    will be rolled backed, and a ``DatabaseException`` will be thrown.
+    In previous versions, ``DBDebug`` was false only in production environment,
+    and different database drivers might throw different exception classes.
+
 Running Transactions
 ====================
 
 To run your queries using transactions you will use the
 ``$this->db->transStart()`` and ``$this->db->transComplete()`` methods as
 follows:
 
+.. literalinclude:: transactions/008.php
+
 .. literalinclude:: transactions/001.php
 
 You can run as many queries as you want between the ``transStart()``/``transComplete()``
 methods and they will all be committed or rolled back based on the success
 or failure of any given query.
 
-.. note:: Since v4.3.0, ``DBDebug`` is true by default in all environments.
-    When ``DBDebug`` is true, if a query error occurs, all the queries
-    will be rolled backed, and an exception will be thrown.
-    In previous versions, ``DBDebug`` was false only in production environment,
-    and different database drivers might throw different exception classes.
-
 Strict Mode
 ===========
 

user_guide_src/source/database/transactions/001.php

@@ -1,5 +1,7 @@
 <?php
 
+// When DBDebug in the Database Config is false.
+
 $this->db->transStart();
 $this->db->query('AN SQL QUERY...');
 $this->db->query('ANOTHER QUERY...');

user_guide_src/source/database/transactions/008.php

@@ -0,0 +1,15 @@
+<?php
+
+// When DBDebug in the Database Config is true.
+
+use CodeIgniter\Database\Exceptions\DatabaseException;
+
+try {
+    $this->db->transStart();
+    $this->db->query('AN SQL QUERY...');
+    $this->db->query('ANOTHER QUERY...');
+    $this->db->query('AND YET ANOTHER QUERY...');
+    $this->db->transComplete();
+} catch (DatabaseException $e) {
+    // Automatically rolled back already.
+}