Simple ways to retrieve data using wpdb

get-data-using-wpdb-global-object.php

<?php
global $wpdb;
// Fetch data from a sepecific table(wp_users) from database 
$get_users = $wpdb->get_results("SELECT * FROM `wp_users`"); 
//Sample output
Array
(
    [0] => stdClass Object
        (
            [ID] => 1
            [user_login] => admin
            [user_pass] => $P$BqTkXEro8BWqK0XIYCngI6jGU7sqag.
            [user_nicename] => admin
            [user_email] => info@admin.com
            [user_url] => 
            [user_registered] => 1900-03-11 07:09:25
            [user_activation_key] => 
            [user_status] => 0
            [display_name] => Administrator
        )

    [1] => stdClass Object
        (
            [ID] => 2
            [user_login] => user
            [user_pass] => $P$BZB1GdUxGlypjyFk6MSIIKjhVC9RRd0
            [user_nicename] => user@mail.com
            [user_email] => user@mail.com
            [user_url] => 
            [user_registered] => 1900-11-19 06:44:53
            [user_activation_key] => 
            [user_status] => 0
            [display_name] => User
        )
  );

// Fetch data from a sepecific column(s) from wp_users table 
$get_users = $wpdb->get_results("SELECT user_email,user_login FROM `wp_users`");
// Specific user
//$get_user = $wpdb->get_results("SELECT user_email,user_login FROM `wp_users` WHERE ID = 1"); 
//Sample output
Array
(
    [0] => stdClass Object
        (
            [user_email] => info@admin.com
            [user_login] => genesis-admin
        )

    [1] => stdClass Object
        (
            [user_email] =>  user@mail.com
            [user_login] =>  user
        )
 )

// Get user email from a sepecific row from database 
// Option 1
$get_user = $wpdb->get_row("SELECT * FROM `wp_users` WHERE ID = 1");
echo $get_user->user_email;
// Option 2
$get_user = $wpdb->get_col("SELECT user_email FROM `wp_users` WHERE ID = 1");
echo $get_user[0];
//Sample output info@admin.com

// Get entire data of a specific column (i.e. user_email) from wp_users
$get = $wpdb->get_col("SELECT user_email FROM `wp_users`");
// Specific user
//$get_user = $wpdb->get_results("SELECT user_email FROM `wp_users` WHERE ID = 1"); 
//Sample output
Array
(
    [0] => info@admin.com
    [1] => user@mail.com
);