WordPress: Access Database From Widget Code

Question

How can I access to my WordPress database and run SQL from the widget code? (I need to access to the settings of one of my plugins from the widget code)

Answer 1

You can check this http://codex.wordpress.org/Class_Reference/wpdb for full documentation. In resume you can do something like the follow from any part of your widget code:

global $wpdb;
$rows = $wpdb->get_results( "SELECT id, name FROM table" );

Answer 2

just include wp-blog-header.php in the file

require('yourpath/wp-blog-header.php');

global $wpdb;

$result=$wpdb->get_results("SELECT * FROM table");

var_dump($result);

Answer 3

If you want to retrieve some information from the database, you can use one of four helper functions to query the database and retrieve the data.

get_results():

This is the function that we looked at earlier. It is best for when you need two-dimensional data (multiple rows and columns). It converts the data into an array that contains separate objects for each row.

get_row():

When you need to find only one particular row in the database (for example, the post with the most comments), you can use get_row(). It pulls the data into a one-dimensional object.

get_col():

This method is much the same as get_row(), but instead of grabbing a single row of results, it gets a single column. This is helpful if you would like to retrieve the IDs of only the top 10 most commented posts. Like get_row(), it stores your results in a one-dimensional object.

get_var():

In many cases, you will need only one value from the database; for example, the email address of one of your users. In this case, you can use get_var to retrieve it as a simple value. The value’s data type will be the same as its type in the database

An example:

<?php
$drafts = $wpdb->get_results("SELECT ID, post_title FROM wp_posts WHERE post_status = 'draft' AND post_author = 5");
foreach ( $drafts as $draft ){
    echo $draft->post_title;
}
?>

Documentation: http://codex.wordpress.org/Class_Reference/wpdb

Source: http://wp.smashingmagazine.com/?p=98071

Hope this helps.