[英]How to not count rows twice if they have same value in mySQL?
I have a visitor tracking system. 我有一个访客跟踪系统。 I track visitor ips and browser.
我跟踪访客ips和浏览器。 I can count total visits (total rows), but how can I count unique visits ?
我可以计算总访问次数(总行数),但是如何计算不重复访问次数呢?
您可以使用Distinct
:
SELECT Count(DISTINCT visits) from Table;
Use GROUP BY
on IP, or IP+browser! 在IP或IP +浏览器上使用
GROUP BY
! SELECT COUNT(ip) FROM yourtable GROUP BY ip
Something like this will give you "unique visitors" as measured by distinct browser/IP hits: 通过不同的浏览器/ IP点击量,类似的东西会给您“独特的访问者”:
SELECT COUNT(*) AS unique_visitors FROM (
SELECT DISTINCT ip, browser FROM visitors
) a
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