Database-related PHP snippets

Issue 135016.

Two templates will be available under the Generate Code action (Alt+Insert):

Connect to Database...
Display Database Table...

The templates only work for MySQL connections. For other connections, the UI is disabled with a meaningful message (or non-MySQL connections are not displayed at all).

Connect to Database:

This template generates code to connect to a given database connection from in the DB Explorer. When invoked, the following dialog is displayed.

+-------------------------------------------------+
| Connect to Database                             |
+-------------------------------------------------+
|                                                 |
| Database Connection:                            |
| [jdbc:mysql://localhost:3306/test           |v] |
|                                                 |
| Connection variable:                            |
| [conn                ]                          |
|                                                 |
|                               [ OK ] [ Cancel ] |
|                                                 |
+-------------------------------------------------+

Generated code:

$conn = mysqli_connect('localhost', 'user', 'password', 'database');
if (!$conn) {
    die('Could not connect to MySQL: ' . mysqli_connect_error());
}
mysqli_query($conn, 'SET NAMES \'UTF-8\'');
// TODO: Insert your code here.
mysqli_close($conn);            

Display Database Table:

This snippet generates code to display the data a HTML table. When invoked, the following dialog is displayed:

+-------------------------------------------------+
| Display Database Table                          |
+-------------------------------------------------+
|                                                 |
| Database Connection:                            |
| [jdbc:mysql://localhost:3306/test           |v] |
|                                                 |
| Table:                                          |
| [ CUSTOMER |v]                                  |
|                                                 |
| Columns:                                        |
| +---------------------------------------------+ |
| | [x] CUSTOMER_ID                             | |
| | [x] DISCOUNT_CODE                           | |
| | ...                                         | |
| +---------------------------------------------+ |
|                                                 |
| Connection variable:                            |
| [conn                ]                          |
|                                                 |
|                               [ OK ] [ Cancel ] |
|                                                 |
+-------------------------------------------------+

Generated code:

echo '<table>';
echo '<tr>';
echo '<th>CUSTOMER_ID</th>';
echo '<th>DISCOUNT_CODE</th>';
echo '</tr>';
$result = mysqli_query($conn, 'SELECT CUSTOMER_ID, DISCOUNT_CODE, ... FROM CUSTOMER');
while (($row = mysqli_fetch_array($result, MYSQLI_ASSOC)) != NULL) {
    echo '<tr>';
    echo '<td>' . $row['CUSTOMER_ID'] . '</td>';
    echo '<td>' . $row['DISCOUNT_CODE'] . '</td>';
    echo '</tr>';
}
mysqli_free_result($result);
echo '</table>';