How to Accurately Count Unique Site Logins in MySQL within the Last Day?

Counting Distinct Site Logins in MySQL

The goal is to determine the number of unique visits to a particular website within the last day, based on the user_id and site_id columns in the cp_visits table. However, the initial query seems to be providing duplicate results for site visits. Let's examine how to rectify this issue.

The provided query attempts to count distinct visits, but it doesn't include a GROUP BY clause, which is crucial for eliminating duplicates. As a result, the query returns multiple rows for each site_id because it doesn't aggregate the results.

To correctly count distinct site logins, we need to group the results by site_id and then count the distinct user_ids within each group. The following modified query accomplishes this:

SELECT
    COUNT(DISTINCT `user_id`) AS `countUsers`,
    COUNT(`site_id`) AS `countVisits`,
    `site_id` AS `site`
FROM
    `cp_visits`
WHERE
    `ts` >= DATE_SUB(NOW(), INTERVAL 1 DAY)
GROUP BY
    `site_id`

In this revised query:

• COUNT(DISTINCT user_id) calculates the number of unique users who visited each site.
• COUNT(site_id) counts the total number of visits to each site.
• GROUP BY site_id` aggregates the results by site_id`, ensuring that we count unique visits for each site.

By applying these modifications, you should now obtain accurate counts of unique site logins for the past day from your cp_visits table.

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