User can post only one comment per day on one page

Question

This code count comments per day on all pages. I want that will count only on one page for 1 day. So my case: on a page with an ID of 1, a user can comment with out any limit, but on a page with an ID of 2, the same user can only comment once per day.

<?php 
global $wpdb,$current_user;
$limit = 5; //this is limit per day per user
$comment_count = $wpdb->get_var( $wpdb->prepare("
    SELECT count(*)
    FROM wp_comments 
    WHERE comment_author = '%s'
        AND comment_date >= DATE_SUB( NOW(), INTERVAL 1 DAY );",
        $current_user->user_login
) );

if ( $comment_count < $limit ) {
    comment_form();
}   
else {
    echo 'exceeded comments limit - '.$limit;
}

Answer 1

Limiting comments per day and per user is already built into your current query. The only thing missing is a check for the post ID. Here's a pretty convenient function/template tag:

/**
 * @param int $limit 
 * @param int $time
 * @param int $ids 
 */
function is_user_limit_reached( $limit = 5, $time = 1, $ids = array() )
{
    global $wpdb;

    // Cast to array
    ! is_array( $limited ) AND $limited = array( $limited );

    // Generate SQL clause
    $ids = ! empty( $ids )
        ? sprintf( " and comment_post_ID in (%s)", join( ",", $ids ) )
        : "";

    // Rows: user_id, comment_date, comment_post_ID
    $count = $wpdb->query( $wpdb->prepare( 
        "select count(*)
        from {$wpdb->comments} 
        where user_id=%d 
            and comment_date >= date_sub( now(), interval %d day )
            %s",
        get_current_user_id(),
        $time,
        $ids
    ) );

    return $count >= $limit;
}

You can use it like this:

if ( is_user_limit_reached(
    10,                      // allowed comments per day
    7,                       // in the last 7 days
    array( 1, 35, 97, 1148 ) // array of post IDs which have a limit
    ) )
{
    echo 'Your limit is already reached. Come back tomorrow';
}
else
{
    comment_form();
}

You could as well switch the comment box template tag on/off, etc. The sky is your limit.