How to insert data into table using plugin.

<?php
/**
* Plugin Name: my-application-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 elh_insert_into_db() {
global $wpdb;
// creates my_table in database if not exists
$table = $wpdb->prefix . "my_table";
$charset_collate = $wpdb->get_charset_collate();
$sql = "CREATE TABLE IF NOT EXISTS $table (
`id` mediumint(9) NOT NULL AUTO_INCREMENT,
`name` text NOT NULL,
UNIQUE (`id`)
) $charset_collate;";
require_once( ABSPATH . 'wp-admin/includes/upgrade.php' );
dbDelta( $sql );
// starts output buffering
ob_start();
?>
<form action="#v_form" method="post" id="v_form">
<label for="visitor_name"><h3>Hello there! What is your name?</h3></label>
<input type="text" name="visitor_name" id="visitor_name" />
<input type="submit" name="submit_form" value="submit" />
</form>
<?php
$html = ob_get_clean();
// does the inserting, in case the form is filled and submitted
if ( isset( $_POST["submit_form"] ) && $_POST["visitor_name"] != "" ) {
$table = $wpdb->prefix."my_table";
$name = strip_tags($_POST["visitor_name"], "");
$wpdb->insert(
$table,
array(
'name' => $name
)
);
$html = "<p>Your name <strong>$name</strong> was successfully recorded. Thanks!!</p>";
}
// if the form is submitted but the name is empty
if ( isset( $_POST["submit_form"] ) && $_POST["visitor_name"] == "" )
$html .= "<p>You need to fill the required fields.</p>";
// outputs everything
return $html;

}
// adds a shortcode you can use: [insert-into-db]
add_shortcode('elh-db-insert', 'elh_insert_into_db');

?>


// http://blog.samelh.com/2015/08/13/create-mysql-database-table-wordpress-insert-data-wpdb-html-form/

<?php
/**
* Plugin Name: my-application-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 elh_insert_into_db() {
global $wpdb;
// creates my_table in database if not exists
$table = $wpdb->prefix . "my_table";
$charset_collate = $wpdb->get_charset_collate();
$sql = "CREATE TABLE IF NOT EXISTS $table (
`id` mediumint(9) NOT NULL AUTO_INCREMENT,
`name` text NOT NULL,
`address` text NOT NULL,
`mobile` text NOT NULL,
UNIQUE (`id`)
) $charset_collate;";
require_once( ABSPATH . 'wp-admin/includes/upgrade.php' );
dbDelta( $sql );
// starts output buffering
ob_start();
?>
<form action="#v_form" method="post" id="v_form">
<label for="visitor_name"><h3>Name?</h3></label>
<input type="text" name="visitor_name" id="visitor_name" />
<label for="visitor_address"><h3>Address</h3></label>
<input type="text" name="visitor_address" id="visitor_address" />
<label for="visitor_mobile"><h3>Mobile</h3></label>
<input type="text" name="visitor_mobile" id="visitor_mobile" />
<input type="submit" name="submit_form" value="submit" />
</form>


<?php
$html = ob_get_clean();
// does the inserting, in case the form is filled and submitted
if ( isset( $_POST["submit_form"] ) && $_POST["visitor_name"] != "" && $_POST["visitor_address"] != "" && $_POST["visitor_mobile"] != "") {
$table = $wpdb->prefix."my_table";
$name = strip_tags($_POST["visitor_name"], "");
$address = strip_tags($_POST["visitor_address"], "");
$mobile = strip_tags($_POST["visitor_mobile"], "");
$wpdb->insert(
$table,
array(
'name' => $name,
'address' => $address,
'mobile' => $mobile
)
);
$html = "<p>Your name <strong>$name</strong> address <strong>$address</strong> and mobile <strong>$mobile</strong>was successfully recorded. Thanks!!</p>";
}
// if the form is submitted but the name is empty
if ( isset( $_POST["submit_form"] ) && $_POST["visitor_name"] == "" && $_POST["visitor_address"] != "" && $_POST["visitor_mobile"] != "")
$html .= "<p>You need to fill the required fields.</p>";
// outputs everything
return $html;

}

// adds a shortcode you can use: [insert-into-db]
add_shortcode('elh-db-insert', 'elh_insert_into_db');


?>

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'
)
);

<?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 */