A CRUD Operations WordPress plugin. Visit https://www.davidangulo.xyz/ for more information.

crud.php

<?php
/*
Plugin Name: CRUD Operations
Plugin URI: https://www.davidangulo.xyz/portfolio/
Description: A simple plugin that allows you to perform Create (INSERT), Read (SELECT), Update and Delete operations.
Version: 1.0.0
Author: David Angulo
Author URI: https://www.davidangulo.xyz/
License: GPL2
*/


register_activation_hook( __FILE__,"crudOperationsTable");
function crudOperationsTable() {
	global $wpdb;
	$charset_collate = $wpdb->get_charset_collate();
	$table_name = $wpdb->prefix . "userstable";
	$sql = "CREATE TABLE `$table_name` (
	`user_id` int(11) NOT NULL AUTO_INCREMENT,
	`name` varchar(220) DEFAULT NULL,
	`email` varchar(220) DEFAULT NULL,
	PRIMARY KEY(user_id)
	) ENGINE=MyISAM DEFAULT CHARSET=latin1;
	";
	if($wpdb->get_var("SHOW TABLES LIKE '$table_name'") != $table_name) {
		require_once(ABSPATH . "wp-admin/includes/upgrade.php");
		dbDelta($sql);
	}
}


add_action('admin_menu','addAdminPageContent');
function addAdminPageContent() {
	add_menu_page('CRUD','CRUD','manage_options',__FILE__,'crudAdminPage','dashicons-wordpress');
}

function crudAdminPage() {
	global $wpdb;
	$table_name = $wpdb->prefix . "userstable";
	if(isset($_POST["newsubmit"])) {
		$name = $_POST["newname"];
		$email = $_POST["newemail"];
		$wpdb->query("INSERT INTO $table_name(name,email) VALUES('$name','$email')");
		echo "<script>location.replace('admin.php?page=crud.php');</script>";
	}
	if(isset($_POST["uptsubmit"])) {
		$id = $_POST["uptid"];
		$name = $_POST["uptname"];
		$email = $_POST["uptemail"];
		$wpdb->query("UPDATE $table_name SET name='$name',email='$email' WHERE user_id='$id'");
		echo "<script>location.replace('admin.php?page=crud.php');</script>";
	}
	if(isset($_GET["del"])) {
		$del_id = $_GET["del"];
		$wpdb->query("DELETE FROM $table_name WHERE user_id='$del_id'");
		echo "<script>location.replace('admin.php?page=crud.php');</script>";
	}
	?>
	<div class="wrap">
		<h2>CRUD Operations</h2>
		<table class="wp-list-table widefat striped">
			<thead>
				<tr>
					<th width="25%">User ID</th>
					<th width="25%">Name</th>
					<th width="25%">Email Address</th>
					<th width="25%">Actions</th>
				</tr>
			</thead>
			<tbody>
				<form action="" method="post">
					<tr>
						<td><input type="text" value="AUTO_GENERATED" disabled></td>
						<td><input type="text" id="newname" name="newname"></td>
						<td><input type="text" id="newemail" name="newemail"></td>
						<td><button id="newsubmit" name="newsubmit" type="submit">INSERT</button></td>
					</tr>
				</form>
				<?php
					$result = $wpdb->get_results("SELECT * FROM $table_name");
					foreach ($result as $print) {
						echo "
							<tr>
								<td width='25%'>$print->user_id</td>
								<td width='25%'>$print->name</td>
								<td width='25%'>$print->email</td>
								<td width='25%'><a href='admin.php?page=crud.php&upt=$print->user_id'><button type='button'>UPDATE</button></a> <a href='admin.php?page=crud.php&del=$print->user_id'><button type='button'>DELETE</button></a></td>
							</tr>
						";
					}
				?>
			</tbody>	
		</table><br><br>
		<?php
			if(isset($_GET["upt"])) {
				$upt_id = $_GET["upt"];
				$result = $wpdb->get_results("SELECT * FROM $table_name WHERE user_id='$upt_id'");
				foreach($result as $print) {
					$name = $print->name;
					$email = $print->email;
				}
				echo "
				<table class='wp-list-table widefat striped'>
					<thead>
						<tr>
							<th width='25%'>User ID</th>
							<th width='25%'>Name</th>
							<th width='25%'>Email Address</th>
							<th width='25%'>Actions</th>
						</tr>
					</thead>
					<tbody>
						<form action='' method='post'>
							<tr>
								<td width='25%'>$print->user_id <input type='hidden' id='uptid' name='uptid' value='$print->user_id'></td>
								<td width='25%'><input type='text' id='uptname' name='uptname' value='$print->name'></td>
								<td width='25%'><input type='text' id='uptemail' name='uptemail' value='$print->email'></td>
								<td width='25%'><button id='uptsubmit' name='uptsubmit' type='submit'>UPDATE</button> <a href='admin.php?page=crud.php'><button type='button'>CANCEL</button></a></td>
							</tr>
						</form>
					</tbody>
				</table>";
			}
		?>
	</div>
	<?php
}

//Visit the tutorial for more information
//https://www.davidangulo.xyz/website-development/how-to-create-crud-operations-plugin-in-wordpress/

this msg will be displayed when i click on delete button...what does it mean
and secondly, i m little bit confuse about this line can u plz explain it to me

I have this problem too.

this msg will be displayed when i click on delete button...what does it mean
and secondly, i m little bit confuse about this line can u plz explain it to me

For anyone in the future coming upon this. You can replace this echo "<script>location.replace('admin.php?page=crud.php');</script>"; with this echo "<script type='text/javascript'> window.location=document.location.href; </script>"; or something like it. or change it how it appears in the browser when you initially go to it. echo "<script>location.replace('admin.php?page=crud%2Fcrud.php');</script>"; for me. Not sure why it's adding the extra. Update: change add_menu_page('CRUD','CRUD','manage_options',__FILE__,'crudAdminPage','dashicons-wordpress'); to add_menu_page(__('CRUD', 'crud'), __('CRUD', 'crud'), 'manage_options', 'crud', 'crudAdminPage','dashicons-wordpress',); also update echo "<script>location.replace('admin.php?page=crud');</script>";. Removing the .php.