updated oracleai_demo.ipynb (#22635)

The outer try/except block handles connection errors, and the inner
try/except block handles SQL execution errors, providing detailed error
messages for both.
try:
    conn = oracledb.connect(user=username, password=password, dsn=dsn)
    print("Connection successful!")

    cursor = conn.cursor()
    try:
        cursor.execute(
            """
            begin
                -- Drop user
                begin
                    execute immediate 'drop user testuser cascade';
                exception
                    when others then
dbms_output.put_line('Error dropping user: ' || SQLERRM);
                end;

---------

Co-authored-by: Chester Curme <chester.curme@gmail.com>

cookbook/oracleai_demo.ipynb

@@ -86,8 +86,7 @@
     "\n",
     "import oracledb\n",
     "\n",
-    "# please update with your username, password, hostname and service_name\n",
-    "# please make sure this user has sufficient privileges to perform all below\n",
+    "# Update with your username, password, hostname, and service_name\n",
     "username = \"\"\n",
     "password = \"\"\n",
     "dsn = \"\"\n",
@@ -97,40 +96,45 @@
     "    print(\"Connection successful!\")\n",
     "\n",
     "    cursor = conn.cursor()\n",
-    "    cursor.execute(\n",
-    "        \"\"\"\n",
-    "    begin\n",
-    "        -- drop user\n",
-    "        begin\n",
-    "            execute immediate 'drop user testuser cascade';\n",
-    "        exception\n",
-    "            when others then\n",
-    "                dbms_output.put_line('Error setting up user.');\n",
-    "        end;\n",
-    "        execute immediate 'create user testuser identified by testuser';\n",
-    "        execute immediate 'grant connect, unlimited tablespace, create credential, create procedure, create any index to testuser';\n",
-    "        execute immediate 'create or replace directory DEMO_PY_DIR as ''/scratch/hroy/view_storage/hroy_devstorage/demo/orachain''';\n",
-    "        execute immediate 'grant read, write on directory DEMO_PY_DIR to public';\n",
-    "        execute immediate 'grant create mining model to testuser';\n",
-    "\n",
-    "        -- network access\n",
-    "        begin\n",
-    "            DBMS_NETWORK_ACL_ADMIN.APPEND_HOST_ACE(\n",
-    "                host => '*',\n",
-    "                ace => xs$ace_type(privilege_list => xs$name_list('connect'),\n",
-    "                                principal_name => 'testuser',\n",
-    "                                principal_type => xs_acl.ptype_db));\n",
-    "        end;\n",
-    "    end;\n",
-    "    \"\"\"\n",
-    "    )\n",
-    "    print(\"User setup done!\")\n",
-    "    cursor.close()\n",
+    "    try:\n",
+    "        cursor.execute(\n",
+    "            \"\"\"\n",
+    "            begin\n",
+    "                -- Drop user\n",
+    "                begin\n",
+    "                    execute immediate 'drop user testuser cascade';\n",
+    "                exception\n",
+    "                    when others then\n",
+    "                        dbms_output.put_line('Error dropping user: ' || SQLERRM);\n",
+    "                end;\n",
+    "                \n",
+    "                -- Create user and grant privileges\n",
+    "                execute immediate 'create user testuser identified by testuser';\n",
+    "                execute immediate 'grant connect, unlimited tablespace, create credential, create procedure, create any index to testuser';\n",
+    "                execute immediate 'create or replace directory DEMO_PY_DIR as ''/scratch/hroy/view_storage/hroy_devstorage/demo/orachain''';\n",
+    "                execute immediate 'grant read, write on directory DEMO_PY_DIR to public';\n",
+    "                execute immediate 'grant create mining model to testuser';\n",
+    "                \n",
+    "                -- Network access\n",
+    "                begin\n",
+    "                    DBMS_NETWORK_ACL_ADMIN.APPEND_HOST_ACE(\n",
+    "                        host => '*',\n",
+    "                        ace => xs$ace_type(privilege_list => xs$name_list('connect'),\n",
+    "                                           principal_name => 'testuser',\n",
+    "                                           principal_type => xs_acl.ptype_db)\n",
+    "                    );\n",
+    "                end;\n",
+    "            end;\n",
+    "            \"\"\"\n",
+    "        )\n",
+    "        print(\"User setup done!\")\n",
+    "    except Exception as e:\n",
+    "        print(f\"User setup failed with error: {e}\")\n",
+    "    finally:\n",
+    "        cursor.close()\n",
     "    conn.close()\n",
     "except Exception as e:\n",
-    "    print(\"User setup failed!\")\n",
-    "    cursor.close()\n",
-    "    conn.close()\n",
+    "    print(f\"Connection failed with error: {e}\")\n",
     "    sys.exit(1)"
    ]
   },