how do you put a custom var within the following type of the below

AND $wpdb->postmeta.meta_value = 'email'

I wish to include a var for 'email'

something similar to

AND $wpdb->postmeta.meta_value = $var

anybody understand how to do that is Wordpress. I believe i have to bind?

re: http://codex.wordpress.org/Displaying_Posts_Using_a_Custom_Select_Query

It is dependent a little on context, but when you really are carrying out a custom query (as, say, a part of a widget) you'd provide it as being a disagreement to WP_Query:

$query = new WP_Query( array( 'meta_value' => 'user@example.com' ) );

Oftentimes this could incorporate a corresponding meta_key for the reason that argument array.

If you wish to customize the presently running query (say, on the category page, only show posts that match a particular criteria) you'd perform that modification throughout the pre_get_posts action. Suggested reading through: Andrew Nacin's You Don't Know Query.

I'd done that using custom query wordpress plugin Go here

else custom your query such as this

<?php

    $args = array('post_type' => 'page','meta_query' => array(array('key' => 'email','value' => 'yes','compare' => '%')));


$var = new WP_Query($args); 

// The Loop

while ( $var->have_posts() ) : $var->the_post();

$P_ID = get_the_ID();



endwhile;



// Reset Post Data

wp_reset_postdata();

Hope it will help