How to show data from database?

<?php
/**
* Plugin Name: my-showdata-plugin
* Plugin URI: http://itechtuto.com
* Description: This plugin show login page details.
* Version: 1.0.0
* Author: Mahtab Habib
* Author URI: http://itechtuto.ocm
* License: GPL2
*/

function show_data_db() {
?>

<table border="1">
<tr>
<th>Firstname</th>
<th>Lastname</th>

</tr>
<?php
global $wpdb;
$result = $wpdb->get_results ( "SELECT * FROM wp_my_table" );
foreach ( $result as $print ) {
?>
<tr>
<td><?php echo $print->id;?></td>
<td><?php echo $print->name;?></td>

</tr>
<?php
}
}

// adds a shortcode you can use: [showtabledata]
add_shortcode('showtabledata', 'show_data_db');


?>

global $wpdb;
/* wpdb class should not be called directly.global $wpdb variable is an instantiation of the class already set up to talk to the WordPress database */
$result = $wpdb->get_results( "SELECT * FROM wp_my_table"); /*mulitple row results can be pulled from the database with get_results function and outputs an object which is stored in $result */
//echo "<pre>"; print_r($result); echo "</pre>";
/* If you require you may print and view the contents of $result object */
echo "ID"." "."Name"."<br><br>";
foreach($result as $row)
{
echo $row->id." ".$row->name."<br>";
}
/* Print the contents of $result looping through each row returned in the result */

<?php
global $wpdb;
$results = $wpdb->get_results("SELECT * FROM wp_names");
print_r($results);
?>

<?php
global $wpdb;
$results = $wpdb->get_results("SELECT name FROM wp_names WHERE girl = 1 and cute = 1 ORDER BY name");

if(!empty($results)) {
foreach($results as $r) {
echo "<p>".$r->name."</p>";
}
} else {
echo "<p>Boo, we couldn't find anything that is in all these groups. Try removing a category!</p>";
}
?>

<?php
global $wpdb;

$gender = esc_sql($_GET["gender"]);
$query = esc_sql($_GET["q"]);

$results = $wpdb->get_results("SELECT name FROM wp_names WHERE $gender = 1 and $query = 1 ORDER BY name");

global $wpdb;

$name = 'Toby';
$gender = 'boy';
$category1 = 1;
$category2 = 0;

$wpdb->insert('wp_names',
array(
'name'=>$name,
'gender'=>$gender,
'category1'=>$category1,
'category2'=>$category2
),
array(
'%s',
'%s',
'%d',
'%d'
)
);