如何在wordpress中激活插件时创建表

i am begineer in wordpress , i want to create table when we activate a plugin .' i have written a code for the same but it is not working . can any one find out what is wrong with this code . so that it will create table successfully

<?php
/*
Plugin Name: dbtable
*/ 
$tbl = $wpdb->prefix . 'member';
function myreg_func(){
    global $wpdb;
    global $tbl;

    $sql="CREATE TABLE IF NOT EXISTS $tbl (id int not null AUTO_INCREMENT,
    em varchar(255) NOT NULL,
    mob BIGING NOT NULL ,
    nm varchar (225) NOT NULL ,
PRIMARY KEY(id))";

require_once(ABSPATH . 'wp-admin/includes/upgrade.php');
        dbDelta($sql);

}
register_activation_hook(__FILE__,'myreg_func');

?>

<?php
/*
Plugin Name: check
*/

function plugin_name_activation() {
    require_once( ABSPATH . '/wp-admin/includes/upgrade.php' );
    global $wpdb;
    $db_table_name = $wpdb->prefix . 'member';
        
        $sql = "CREATE TABLE " . $db_table_name . " (
            `id` bigint(20) UNSIGNED NOT NULL AUTO_INCREMENT,
            `em` varchar(100) NOT NULL ,
            `mob` int(20) NOT NULL,
             `nm` varchar (225) NOT NULL ,
            
            PRIMARY KEY (`id`)
        ) ;";
        dbDelta( $sql );
    
}
register_activation_hook(__FILE__, 'plugin_name_activation');

?>

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