meta query and code example

Example 1: wordpress meta_query relation

$results = query_posts( array(
    'post_type' => 'event_id',
    'meta_query' => array(
        'relation' => 'AND',
        array(
            'relation' => 'OR',
            array(
                'key' => 'primary_user_id',
                'value' => $user_id
            ),
            array(
                'key' => 'secondary_user_id',
                'value' => $user_id
            )
        ),
        array(
            'key' => 'date',
            'value' => array( $start_date, $end_date ),
            'type' => 'DATETIME',
            'compare' => 'BETWEEN'
        )
    )
) );

Example 2: meta_value wordpress

$meta_query_args = array(
    'relation' => 'OR', // Optional, defaults to "AND"
    array(
        'key'     => '_my_custom_key',
        'value'   => 'Value I am looking for',
        'compare' => '='
    )
);
$meta_query = new WP_Meta_Query( $meta_query_args );