<?php
// Creating tables in Single site installations
function on_activate() {
    create_table();
}

function create_table() {
    global $wpdb;
    $table_name = $wpdb->prefix . 'table_name';

    if( $wpdb->get_var( "show tables like '{$table_name}'" ) != $table_name ) {

        $sql = "CREATE TABLE " . $table_name . " (
            id mediumint(9) NOT NULL AUTO_INCREMENT,
            col VARCHAR(100) NOT NULL,
            PRIMARY KEY  (id)
        );";

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

        add_option( EmailLog::DB_OPTION_NAME, EmailLog::DB_VERSION );
    }
}

register_activation_hook( __FILE__, 'on_activate' );
?>