Date Gaps or Continuous Date Ranges

WITH 
    numbered AS
    (
        SELECT  
            ad_id, 
            eventdate,
            DENSE_RANK() OVER (PARTITION BY ad_id ORDER BY eventdate) AS rn
        FROM    
            facebook_spend_data
        WHERE
            ad_id = '6245581352190'
        GROUP BY
            ad_id, eventdate
    ),
    date_groups AS
    (
        SELECT
            ad_id, 
            eventdate,
            rn,
            DATEADD(day, -rn, eventdate) AS grp_date
        FROM 
            numbered
    )
SELECT
    ad_id,
    MIN(eventdate) interval_start,
    MAX(eventdate) interval_end,
    1 + MAX(eventdate) - MIN(eventdate) AS consecutive_days
FROM date_groups
GROUP BY ad_id, grp_date
ORDER BY ad_id, interval_start;

WITH 
    previous_days AS
    (
        SELECT
            ad_id,
            eventdate,
            LAG(eventdate) OVER (partition by ad_id ORDER BY eventdate) previous_date
        FROM
            facebook_spend_data
        WHERE
            ad_id = '6245581352190'
        GROUP BY
            ad_id, eventdate
    )
SELECT
    ad_id, 
    eventdate,
    previous_date,
    DATEDIFF(day, previous_date, eventdate)
FROM
    previous_days;