问题:

I am checking website entrys that are recorded in a database

columns: browser, click_type_id, referrer, and datetime

if multiple rows have the same browser, click_type_id, and referrer and are timestamped (occur within 1 minute of one another) they are considered a duplicate.

I need a sql statement that can query for these duplicates based on the above criteria.

Any help is appreciated.

回答1:

SELECT
     T1.browser,
     T1.click_type,
     T1.referrer,
     T1.datetime,
     T2.datetime
FROM
     My_Table T1
INNER JOIN My_Table T2 ON
     T2.browser = T1.browser AND
     T2.click_type = T1.click_type AND
     T2.referrrer = T1.referrer AND
     T2.datetime > T1.datetime AND
     T2.datetime <= DATEADD(mi, 1, T1.datetime)

回答2:

To prevent inserts

INSERT MyTable (browser, click_type_id, referrer, [datetime])
SELECT
    @browser, @click_type_id, @referrer, @datetime
WHERE
    NOT EXISTS (SELECT *
        FROM
           MyTable M2
        WHERE
           browser = @browser AND click_type_id = @click_type_id AND referrer = @referrer
           AND
           [datetime] < DATEADD(minute, -1, @datetime))

To find in existing data (relies on smalldatetime accuracy and may help to avoid issues as per comment to question)

SELECT
   browser, click_type_id, referrer, COUNT(*)
FROM
   MyTable
GROUP BY
    browser, click_type_id, referrer, (CAST [datetime] AS smalldatetime)
HAVING
    COUNT(*) > 1